Victor Willing’s evocation of a standing nude woman reveals the fragility as well as the inexorable ‘presence’ of the individual person of flesh and blood. It is this ‘natural’ person that the law and the rule of law aim to protect and enable, by way of institutional facts and features such as legal personhood, property rights, liability, and various competences and their restrictions. Note that in law, a legal subject is never alone - legal norms are only relevant within a web of relationships and this web plays out between citizens (and e.g. corporations), or between citizens (and e.g. corporations) and the state. Also note that the protection offered always depends on the state’s powers to enforce such protection. Without the state, there is no private law and no criminal law; everyone will have to fend for themselves.
Computer science can be divided in a plethora of different subdisciplines, while division may depend on whether one comes from e.g. electrical or electronic engineering, from mathematics, software engineering, statistics, cognitive science or machine learning. Law and the study of law is most often divided in three major domains: private, public and criminal law. These domains have own principles, own vocabularies and structures, geared to the type of relationships they concern. For instance, when relationships are vertical, as in public and criminal law, different principles apply than when they are considered horizontal, as in private law.
This chapter will first explain how these domains differ, based on a set of conceptual distinctions. This provides the foundations for the subsequent introduction of the core structure, vocabulary and underlying principles of each domain. This is pivotal for a proper understanding of more specified domains such as data protection law, cybercrime and copyright that comprise the second part of the book.
If we ask the question of ‘what law does’, the answer is as simple as it is complex: law creates legal effect. The complexity resides in how this is done, even though here again the answer seems simple: this depends on the applicable legal conditions. To identify the relevant legal conditions, we must search the sources of law (a concept with a very specific meaning, as explained in chapter 2).
In chapter 2 we introduced law as a system of legal norms, notably as a combination of primary and secondary legal rules. These rules form a complex architecture with multiple dimensions (e.g. local, national, international and supranational rules; general and more specific rules; prior and posterior rules; legislation and case law that enact and interpret rules; and, principles that are derived from the implied philosophy of positive law).
To clarify the difference between private, public and criminal law, we will add a complementary perspective to frame the law. Next to describing law as a unity of primary and secondary rules and underlying principles, we will picture law as a system of legal relations between legal subjects, with regard to legal objects.
Property rights, such as ownership, are often described in terms of the relationship between a legal subject (e.g. a natural person or a corporation) and a legal object (e.g. a house or a receivable), stating that the subject has a right in the object. To better understand what this means we will describe property rights in terms of the relationships between legal subjects, with regard to a legal object.
In figure 1 we can see that a legal subject with an absolute right in a legal object imposes a duty of non-interference for ALL other legal subjects, with respect to her right in this legal object. Property rights are thus absolute rights in this particular sense: all others must refrain from interfering with these rights. Absolute, here, does not refer to unlimited. Property rights may be limited by e.g. a prohibition to abuse the right, or by human rights. For instance, if I own a house and rent it out to someone, my property right in the house is not unlimited; I cannot enter the house at will, because this may violate the right to privacy of the person who rents the house. Though not unlimited,1 absolute rights can in principle be enforced against all legal subjects.
In figure 1 we can also see that a relative right only plays out between a restricted set of other legal subjects. For instance, a contract usually generates two legal effects, i.e. the legal obligations to which the contract commits the parties. In the case of a contract of sale, one party will have to pay the agreed price, the other party will have to deliver the agreed good or service. Both parties have the legal right that the other party complies with her legal obligation. But, other than in the case of property rights, these rights only apply to the relevant party to the contract. There is no duty for other legal subjects to comply with the agreed legal obligations. Relative rights can only be enforced against specific legal subjects.
Many attempts have been made to find conclusive criteria to distinguish private and public law. For instance:
Whenever the government is involved, we are in the domain of public law.
This would mean that if a government agency buys pencils, the contract would be ruled by public law. The seller of the pencils may object that this exempts the government from the Rule of Law, as this would exempt it from e.g. the duty to pay compensation in the case of breach of contract. Therefore, in constitutional democracies, this criterion is not conclusive. When the government buys pencils, private law applies.
Another criterion suggests that:
Whenever the public interest is involved, we are in the domain of public law.
Though this sounds plausible, it seems to be in the public interest that parties to a contract are bound to comply with the obligations to which they have committed. If the criterion of the public interest is applied, this would mean that such compliance is part of public law. This is clearly not the case. In constitutional democracies, the inverse does pertain; the government is bound to always act in the public interest.
Finally, yet another criterion proposes that:
Public law entails that the enforcement initiative is with the government.
In private law, enforcement is left to private parties. They can go to court or e.g. involve a bailiff, but the government will not take the initiative to enforce compliance with a contract. This is connected with the idea that in private law, parties are autonomous as to the content of a contract but also with regard to how they respond to defaulting by the opposite party. This might lead one to conclude that when public law is at stake, the enforcement initiative is with the government. However, in administrative law, citizens can take the initiative to object or appeal against a decision made by the administration. This does not turn the legal remedies of citizens into private law.
Instead of trying to develop criteria, we can resort to a simple inventory. Public law consists of: (1) constitutional law, (2) administrative law, (3) international public law. We could say that in these subdomains the government acts ‘as such’, i.e. in its capacity of a public authority, under the rule of the legality principle. As soon as the government acts in its capacity as a private party, private law will apply.
It follows that private law is that part of law where the government ’as such’ does not play a role. We must remind ourselves, however, that private law is an artificial construction, just like public law and criminal law. It has been instituted by the legislature and will be enforced and fine-tuned by the courts. In that sense its construction is based on the attribution of legal powers to legislate and adjudicate and thus depends on public law (the constitution). It is tempting to frame private law as ‘given’ or ‘natural’ law, as if it is merely the written articulation of an existing unwritten private law. This temptation must be resisted as it hides the fact that legislators and courts make many choices when deciding on the content of private law, while these choices basically constitute and regulate economic markets. It is not the market that dictates the power of law, but the law that ‘affords’ a specific type of economic market (that may in turn enhance or diminish legal protection).
Above, we observed that in a constitutional democracy, the government must always act in the public interest. This raises the question of the purpose of private law. Individual citizens are not by default required to act in the public interest, instead private law gives them the legal tools to act strategically in their own interest. This is related to the idea of individual autonomy that seems to be the hallmark of private law. Private law provides legal norms meant to create a private sphere where companies, consumers, employees and employers, service providers and users are in principle free to conduct a business, to conclude contracts and to navigate their personal, social and institutional environments as they wish. Private law thus aims to create and sustain societal trust, based on legal certainty. For instance, when one buys a house, one can in principle be sure that the owner can be forced to deliver the house after the price has been paid. And, when a person wrongfully causes damage to another, the other must in principle be sure that the tortfeasor can be forced to compensate for the damage. I qualify these general rules by inserting ‘in principle’, because exceptions apply.
Next to individual autonomy and societal trust, private law is also about fairness. For instance, in shaping economic markets, private law not only ensures that agreed prices must be paid and goods delivered, but subdomains such as e.g. consumer law, non-discrimination law, competition law, product liability and unfair contract terms law have dimensions of fairness. Notably to compensate the lack of bargaining power of weaker parties (e.g. consumers) or to protect specified groups against unjustified discrimination. This demonstrates that private law can be restricted, for instance by constitutional limitations and international human rights law, but also by administrative law. House owners have full disposition of their property, but administrative law may restrict their competence to renovate the house, for instance based on safety requirements that are part of administrative law.
The purpose of public law is the public interest or benefit, in Latin the res publica, which resulted in the idea of a Republic. The public interest has a very broad meaning and basically requires an assessment of a diversity of public interests, which may be incompatible in concrete situations. Public law concerns, for instance, safety and security, welfare, public health, care for the elderly, public education, public traffic management, full employment, public housing, etc. Public law, notably administrative law is restricted by the legality principle that requires a legal basis for all acts and decisions of the government. This legal basis can be very general if the actions or decisions do not entail negative consequences, but if negative implications can be expected, the legal basis must be specific in what it allows, for what purpose and under which precise conditions. If the government, for instance, wants to disown a person to enable the construction of a new public road, highly specific conditions apply, and the person must be compensated. The legality principle demands that the government always acts within the limits set by the written or unwritten Constitution (that attributes powers to the government). This is directly related to the fact that under the Rule of Law, legal norms are both constitutive and limitative of the legal powers they attribute (cf. chapter 2). On top of that, international human rights law and other treaties to which a state is bound, will further restrict the powers of the government.
Some legal norms are mandatory, which means that they cannot be overruled by contractual or other norms. In public law, most of the norms are mandatory, both when addressing citizens (e.g. prescribing with what conditions they must comply to obtain a building permit) and when addressing the government (e.g. prescribing under what conditions a municipality must grant the building permit). In private law, many legal norms are default, especially in the domain of contract law, meaning that such norms only apply if parties have not agreed otherwise.
Returning to the perspective of law as a complex architecture of legal relationships between legal subjects, we can depict public law as follows:
Public law is based on a relationship between each individual legal subject and the state. This is an example of distributive equality, meaning that all citizens are at equal distance from the state, being entitled to equal respect and concern (chapter 2). This creates a specific type of equality amongst citizens, who – even if they remain strangers to each other – share an equivalent relationship to the same state. Based on this relationship to the state, citizens can develop legitimate mutual expectations, knowing that the state can enforce such expectations if they are ‘covered’ by legal norms.
Let’s look at a typical exam multiple choice question on the topic of the difference between private and criminal law:
I. If downloading of illegally provided content is unlawful, it is necessarily punishable.
II. If someone commits a crime the victim can initiate proceedings.
I and II are both correct.
I is correct, II is not correct.
I and II are both incorrect.
I is not correct, I is correct.
This question aims to test a proper understanding of the difference between an action being unlawful and an action being punishable. Clearly, for an action to be punishable, it must be unlawful. It would be against the criminal law legality principle to punish a person if such action was not clearly defined as being unlawful. But the criminal law legality principle demands more than that. It requires that an action can only be punished if it was clearly defined as a criminal offence at the time of committing the offence. If not, the action does not qualify as an offence. This means that most unlawful actions are not criminal offences.
Criminal conduct is a subset of unlawful conduct. Not everything that is unlawful or illegal is punishable. Whether something is unlawful and/or criminalised conduct depends on whether it has been defined as such in the objective law, which also defines any subjective rights a person may have.
Objective law is the unity of primary and secondary rules, and the implied principles of law, that is valid within a specific jurisdiction. A subjective right is a right attributed to a legal subject by the objective law; a legal right therefore depends on the objective law that grants it. In chapter 2 we discussed the concept of positive law, which is close to that of objective law. Positive law is the law that is in force in a specific jurisdiction. The emphasis here is on the ‘posited’ or artificial nature of modern law. Objective law refers to the same, but juxtaposes the assemblage of rules and principles to the set of individual rights, highlighting the fact that subjective rights depend on objective law.
Who or what is a legal subject is not given, but depends on objective or positive law. A legal subject (a natural person or a legal person) is an entity capable of acting in law, bearing legal rights and legal obligations in relation to other legal subjects. In contemporary positive law we distinguish between two types of legal subjects: a natural person or a legal person. Positive law decides what entities have legal personhood. Think of corporations, municipalities or the state itself. These all have standing in law, they can conclude contracts and be held liable. In principle positive law could attribute legal personhood to animals or robots. We will return to this point in chapter 9.
A legal object is an entity that is the object of a specific legal relationship between legal subjects. Think of a legal good such as an intellectual property right, a tangible, or a specific obligation. If I conclude a contract with one of my students, to sell her a book, the book is the legal object. More precisely, the property right of ownership is the legal object that will be transferred.
Private law can be subdivided in e.g.: family law (marriage, inheritance); contract law (general, specific); property law (transfer of ownership); and tort law (general, specific). In this monograph we will not discuss family law, but focus on contract, property and tort law.
Private law contains the legal norms that regulate relationships between legal subjects at a horizontal level, thus excluding the government acting ‘as such’. Horizontal does not mean that legal subjects are equal in the sense of having the same economic or other power. It means that they are formally considered as equal, capable of determining their own position in law; they can e.g. conclude contracts, sell their property and be held liable for unlawful wrongdoing. As indicated above, private law respects the autonomy of individual persons but also contributes to such autonomy by enabling them to act strategically within the private sphere, as long as they act within the bounds of the law. Other ways of contributing to individual autonomy can be detected in e.g. consumer law, competition law, where they aim to compensate weaker parties with less bargaining power. We will now discuss property law, contract law and tort law.
Alice has a book, Bob has a house, Eaves has a wonderful surname (Dropping). Legally speaking, the question is what ‘has’ means. Does Alice own the book, does Bob rent the house, can Eaves sell her name? These questions bring us into the heart of property law. A surname cannot be sold, it is not a property – even though it clearly belongs to Eaves and not to another. But does ‘having’ a house in the sense of ‘renting’ turn the house into the property of Bob? Renting a house means that one has the right to live in the house of the owner, based on the freedom of the owner to rent out the house. In most jurisdictions, there is a subdomain of private law dedicated to the renting of real estate (including protection of those who rent a home against arbitrary decisions of the owner).
What if Alice has borrowed the book and sells it to Bob? In this case Alice first held the book for another (the owner from whom she borrowed). When she sold it to Bob she possessed the book (this means that from that moment onwards she is holding the book for herself). Though she possessed the book, she did not own it, because ownership would imply possession with right. So, Alice first held the book, then possessed it, but never owned it. The question is whether Bob owns the book, after buying it from Alice.
This is a question concerning transfer, possession and ownership of movables or tangibles. This question must be answered with regard to a specific jurisdiction, because private law is not the same in each country. Because positive law is posited, different legislatures and courts can ‘posit’ different rules about transfer, possession and ownership of movables. Let’s take an example from the Netherlands Civil Code, art. 3:84 CC (requirements for a transfer):
The transfer of property requires a delivery pursuant to a valid legal basis by the person with power of disposition over that property.
This means that the law requires that 3 legal conditions are fulfilled to achieve the legal effect of a transfer of movable property:
Valid legal basis or title
Power of disposition
Note that these conditions are cumulative; each condition must be fulfilled. We will now check whether the property of the book is transferred. For a delivery it would be enough that Alice hands over the book to Bob. If Alice has concluded a valid contract of sale with Bob, there is a valid legal basis or title. However, since Alice is not the owner, she lacks power of disposition. One of the crucial legal powers that the law attributes to ownership, is the power of disposition, or the freedom to share, sell, give or even destroy the object of ownership. It seems to be that Alice cannot transfer property, because she has no power of disposition.
Now, check Article 3:86 CC (Lack of power of disposition)
A transfer of a movable thing (…) by an alienator without power of disposition is nevertheless valid if the transfer was not performed gratuitously and the acquiring party acted in good faith.
Here we see that the legal effect that Bob wants to achieve, transfer of the book, can be reached despite the fact that Alice (the alienator) has no power of disposition. It requires that the following legal conditions are fulfilled:
Transfer not for free
Good faith of the acquiring party
Again, note that the conditions are cumulative. The book is a movable, and the sale presumes that a price has to be paid so the transfer is not for free. The final condition concerns the good faith of Bob. If he knew that Alice borrowed the book, the ownership will not be transferred. If he was not aware of that, he will become the owner. Note that this implies that Alice has transferred something that she did not have herself: the ownership of the book. This is an exception to a rule in private law: nemo dat quod non habet (no one gives what they do not have). The exception is based on the need to ensure trust in economic relationships. In this case the buyer is protected because they should be able to assume that a person who possesses a movable is the owner. The idea is that this smooths day-to-day economic transactions, which would become cumbersome if one first has to figure out whether the person who is selling is actually the owner.
Now, what if Alice stole the book? The Netherlands legislature wants to contribute to a transparent marketplace, where people can trust that items clearly possessed by the seller will become their property (if they have no reason to believe the seller is not the owner). However, the legislature does not want to reward the theft of goods. Therefore, we have art. 3:86 CC:
3. The owner of a movable thing who has lost possession of it because it was stolen from him may, in spite of the previous paragraphs, always claim his property back from every possessor within three years after the theft, unless:
a. the stolen object has been acquired by a natural person who, when he acquired it, did not act in the pursuance of his practice or business, and who had received it from an alienator who sells these or similar objects regularly to the public making use of a business premises destined for that purpose and who acted, when he passed to stolen object to the acquiring party, in the conduct of his practice or business, yet not as an auctioneer;
b. or the stolen object concerns money or negotiable documents for a claim to order or to bearer.
Again, we first identify the relevant legal effect. In this case the legal effect concerns the owner of the stolen book. She can claim back (revindicate) her property, if the following legal conditions apply:
less than 3 years have passed since the book was stolen, and
2.a Bob is not a natural person, or
2.b Bob is acting in the context of his practice or business, or
2.c Alice does not regularly sell second hand books to the public in business premises destined for that purpose, or
2.d Alice did not pass the book to Bob in the conduct of her business, or
2.e Alice passed the book to Bob as an auctioneer, and
3. the book does not count as money or negotiable documents for a claim to order or to bearer
Note that paragraph 3 of art. 3:86 consists of one positive condition, followed by a series of negative conditions under 3.a and 3.b. These conditions are not cumulative, if any of them applies, the legal effect (of revindication) cannot be attributed.
If we assume that Alice does not have a business of selling things like books, the original owner will be able to revindicate her book from Bob within 3 years of the theft.
This piece of legislation nicely demonstrates how the law protects the interests of different parties and the general interest of legal certainty and trust in business transactions.
Can Bob sell the house he rents to Eaves? The first question we need to confront is whether selling is a matter of property law or contract law. When we ask if Bob can sell a house, we are inquiring whether he can conclude a contract with Eaves about the sale of the house. This is a question of contract law, which is a subdomain of the law of obligations. Let us check the legal definition of a contract in art. 6:213 CC on the ‘Definition of an obligatory agreement’
An agreement (contract) in the sense of this Section is a more-sided (multilateral) juridical act under which one or more parties have subjected themselves to an obligation towards one or more other parties.
The legal effect consists of a valid obligatory agreement, which comes into existence if the following legal conditions are fulfilled:
a more-sided (multilateral) juridical act
by which one or more parties subject themselves
to an obligation towards one or more other parties
These conditions are cumulative, the legal effect only occurs if all 3 conditions apply. This raises the question of what is meant by a ‘juridical act’, defined in art. 3:33 CC on ‘Intention and Declaration’:
A juridical act requires the will (intention) of the acting person to establish a specific legal effect, which will (intention) has to be expressed through a statement of the acting person.
The legal effect is the existence of a valid juridical act, and the legal conditions are:
the will or intention of the acting person to achieve a specific legal effect
the will has been expressed through a statement of the acting person
So, in principle, if Bob and Eaves expressed their intention to transfer property (Bob) and to pay a price, which means to transfer money (Eaves), they have concluded a valid agreement. In this case the agreement is a contract of sale, which generates two legal obligations: (1) the buyer must pay the agreed price, (2) the seller must transfer property.
The second question we confront, if Bob actually manages to sell the house to Eaves, is whether he can transfer the property of the house to Eaves. This is a matter of property law, just like the transfer of movable property. As we have seen above, art. 3:84 CC requires the power of disposition to transfer property. Since Bob is not the owner he lacks that power. In the case of real estate, the exception for the transfer of movables does not apply. In principle Bob can, therefore, sell the house but he cannot transfer the property. However, after the contract of sale has been made, he will not be able to fulfil his legal obligation to deliver the house, and thus Bob will be ‘in breach of contract’.
What if Eaves had counted on the transfer of property and suffers damage due to Bob’s incapacity to deliver the house? We now check art. 6:74 CC on ‘requirements for a compensation for damages’:
1. Every imperfection in the compliance with an obligation is a non-performance of the debtor and makes him liable for the damage which the creditor suffers as a result, unless the non-performance is not attributable to the debtor.
The legal effect here is the liability for damages, the legal conditions are:
there is non-performance of the debtor (the one who did not perform)
as a result of an imperfection in the compliance with their obligation
the non-performance is attributable to the debtor
So, in principle: Bob can sell the house, but he cannot deliver it. This is a salient example of the difference between absolute and relative rights, as discussed above: absolute rights are rights with regard to a good, that can be sustained against everybody; they create a duty of non-interference for all others. This is why their publicity is crucial; anybody must be able to check their legal effect. For tangibles possession is the default publicity: when someone holds a tangible for themselves we can assume it is theirs. For real estate we have a public registry where people can check who has a property right; since nobody carries their real estate with them, possession does not mean much. Relative or personal rights are rights that can only be sustained against a specific person or persons; since third parties cannot derive rights from relative rights that do not concern them, and have no obligations to respect relative rights that do not concern them, they have no need to know, so by default such rights are not registered.
In private law there is only a limited set of absolute rights, which is again related to the fact that anybody had an obligation not to interfere with these rights. In most jurisdictions this set of property rights consists of: ownership, freehold, leasehold, servitude, right of superficies, apartment right, usufruct, pledge and mortgage, and intellectual property rights (e.g. copyright, patent). We speak of this as a closed system of property rights, as new rights cannot be created at will by individual legal subjects, even if they would agree. If the reader wants to know more about the content of these rights (their legal conditions and the ensuing legal effect), they are advised to check the relevant literature (under the references of this chapter).
Relative rights usually form an open system, where people can create new rights by way of contract (next to the contract of sale or rent or employment). Non-contractual relative rights are: tort (e.g. violation of privacy), undue performance, unjustified enrichment. In this chapter we will deal with the most important type of non-contractual right, based on tort liability.
To understand tort law, we shall now distinguish a juridical act from a juridical fact. As discussed above, a juridical act is an action that aims for the legal effect the law attributes, for instance the validity of a contract, the validity of a will, or legislation that is in force. Often, however, the law attributes legal effect even if this was not intended. A juridical fact is an occurrence, status or act that is legally relevant because the law attributes legal effect, irrespective of intent, for instance birth (attribution of legal subjectivity), death (inheritance), and tort (injunction and/or compensation of damage).
To understand the complexities of tort law I will discuss the famous Dutch ‘cellar hatch case’, which was decided in 1965 by the Netherlands Supreme Court.2 The facts of the case are as follows. In 1961, in Cafe De Munt at Singel 522 in Amsterdam, Duchateau goes to the loo and falls into a cellar that was open, because ‘Sjouwerman’ (working for Coca Cola) was busy putting drinks in the cellar and left the hatch open. Duchateau suffered serious harm and sued Coca Cola for the damages. He did not sue Sjouwerman himself, because Coca Cola had deeper pockets and by default an employer is liable for damage caused by one of its employees, if it has been caused during normal working operations.
The legal question at stake was, whether Sjouwerman should have taken into account that people may not be as cautious as required to prevent the accident? This is a crucial question as the default of private law is that everyone carries their own damages. Some people may have bad luck due to disease, an accident or whatever, but unless the law makes an exception, such bad luck cannot be charged to another. One of these exceptions is a tort.
In the Netherlands Civil Code a tort is defined in art. 6:162:
A person who commits a tortious act (unlawful act) against another person that can be attributed to him, must repair the damage that this other person has suffered as a result thereof.
The legal effect is a legal obligation ‘to repair the damage’ (to pay compensation), and the cumulative legal conditions are:
a person has committed a tortious act (an unlawful act),
that can be attributed to him (attribution of act to tortfeasor),
against another person, who suffered damage (damage),
the damage is the result of the tortious act (causality between act and damage).
To decide whether an act (including an omission) ‘counts as’ a tortious act, the second paragraph of art. 6:162 CC stipulates:
As a tortious act is regarded a violation of someone else’s right (entitlement) and an act or omission in violation of a duty imposed by law or of what according to unwritten law has to be regarded as proper social conduct, always as far as there was no justification for this behaviour.
To qualify as a tortious act, 3 alternative conditions and 1 cumulative condition apply:
the act was a violation of another’s right, or
the act was a violation of a legal duty, or
the act violates an unwritten legal duty, and
there was no justification for the act.
To decide whether the tort can be attributed to the tortfeasor, the third paragraph of art. 6:162 CC stipulates:
A tortious act can be attributed to the tortfeasor if it results from his fault or from a cause for which he is accountable by virtue of law or generally accepted principles (common opinion).
To qualify as an act ‘of the tortfeasor’, the following alternative conditions apply:
The act results from his fault (culpability), or
The act results from a cause for which he is accountably by virtue of law or generally accepted principles (risk liability).
Beyond these two types of attribution (of the act to the tortfeasor), most jurisdictions distinguish between: fault liability (culpability), vicarious liability (where another is liable for a tortious act, e.g. in the case of an employer being liable for the tortious acts of their employees), and strict liability (e.g. of an owner for their animal or the building they own).
Some jurisdictions also discriminate between risk liability as an inversion of the burden of proof, meaning that exculpation is possible, and strict liability where exculpation is not possible. This relates to the attribution of causality: if there is damage and the damage could reasonably likely have been caused by the tortious act, causality is assumed. In the case of risk liability, the tortfeasor can still prove they did not ‘cause’ the damage (often termed a probatio diabolico). In the case of strict liability, such counter-proof is not allowed.
To decide whether Coca Cola was liable for the harm to Duchateau, because of Sjouwerman’s behavior (vicarious liability), the court must decide whether the act of Sjouwerman was a violation of an unwritten ‘duty of care’. The court of first instance decided that Sjouwerman was not at fault, because Duchateau should have been more careful himself. The court of appeal, however, found Sjouwerman at fault, notably for not taking into account that customers may not be as prudent as might be expected. Considering the major consequences of an accident, Sjouwerman should have taken safety measures to prevent this. The Supreme Court found that the court of appeal had used correct criteria to assess whether Sjouwerman violated his duty of care towards the customers of the café, notably:
the probability that visitors of the café are not as cautious necessary, and
the probability that this lack of caution will lead to accidents, and
the seriousness of the harm that may result, and
the extent of the burden of safety measures.
Here we see that private law contains a number of generic concepts, such as ‘duty of care’ that require a case-specific assessment of what is at stake, while taking into account that the assessment criteria must be generalizable to subsequent cases – in line with both legal certainty and justice (treating similar cases similarly in a foreseeable manner). This makes legal judgment a crucial but complex and reflective practice, demanding acuity and ingenuity of the court in the face of changing circumstances and the competing demands of legal certainty, instrumentality and justice. It highlights the need to assess and interpret the facts of the case in light of the applicable legal framework, and the simultaneous need to identify and interpret the applicable legal norm in light of the legal framework and the facts of the case. All this demonstrates the inherent contestability of judgments, both regarding the identification of relevant facts and the interpretation of the legal norm. In turn, all this highlights the centrality of both interpretation and legal reasoning in the study and the practice of law.
In chapter 8 we will revisit tort law in more detail, in relation to privacy harms and cyber torts.
As discussed above, public law must be justifiable in terms of the public interest. It may be that it is in the public interest that the state considers and defends its own interests, for instance in situations of emergency. This, however, cannot be assumed: the interest of the state should not be conflated with the public interest.
In a constitutional democracy, the state must not only (1) act with an eye to the public interest, but also (2) act within the confines of the legality principle and (3) treat citizens with equal respect and concern. These requirements similarly apply to criminal law, which involves one of the most invasive competences of the state, namely the so-called ius puniendi (the right to punish). Legal scholarship often qualifies criminal law as a subdomain of public law, as it constitutes and regulates the conduct of the state. It contains the secondary rules that clarify which primary rules are protected by means of criminalization. This can be gleaned from the articulation of criminal offences, e.g.: ‘Whoever commits murder will be punished with maximum 15 years of imprisonment.’ This is clearly not a primary rule; it does not state that murder is prohibited. Instead, it states under what legal conditions punishment is lawful. Criminal law, in that sense, depends on the vertical relationship between a state and its citizens – as in public law.
However, the secondary rule manifestly assumes the primary rule; one cannot be punished if one’s conduct is not unlawful. That is why some jurisdictions do not qualify criminal law as a subdomain of public law, emphasizing that the primary rules concern the horizontal relationships between legal subjects. One could say that criminal law shows the mutual dependencies between the horizontal and the vertical relationships of a legal system.
Public law regards, on the one hand, legal relations between a state (acting as such) and its citizens, and, on the other hand, the legal relationships between states. The first concerns constitutional and administrative law, the second concerns international public law. Constitutional law and international public law have many dependencies, in the first place because the constitution determines if, to what extent and under what conditions international law overrules national law in case of a conflict between both. Second, international law may stipulate its own priority, for instance in the case of ius cogens, i.e. law that applies without exception to all states (e.g. the prohibition of crimes against humanity and genocide).
International public law will be discussed extensively in the next chapter (4). Here, we focus on constitutional and administrative law.
Constitutional law attributes competences (1) to legislate (Acts of Parliament) and to regulate (Regulatory Policies), (2) to act and decide based on its public authority (traffic management, environmental protection, decisions on tax or social security), and (3) to adjudicate (private law, criminal law, administrative law). These competences are attributed to the legislator (e.g. parliament, municipality), to public authorities (cabinet ministers, supervisors, tax authorities, environment agencies), and to courts (defining their jurisdiction).
Constitutional law restricts the competences it attributes, by requiring specific safeguards which constitute legal conditions that limit the exercise of the powers that have been allocated. This clearly shows the constitutive and limitative nature of the attribution of powers in a constitutional democracy. These limitations may concern procedural or substantial prerequisites, e.g. making sure that privacy is not unnecessarily infringed, unjustified discrimination is prevented and the freedom of speech is not violated.
Administrative law regulates the conduct of the government and other agencies with public authority, e.g. in the domain of environmental law, student grants law, public health law, and tax law.
Based on the legality principle, administrative law requires that actions and decisions of public authorities have a legal basis. This legal basis constitutes their competence to e.g. maintain roads, to take decisions about individual taxes or social security, and to impose policy rules on the industry regarding specified pollution (emission thresholds). Citizens addressed by the decisions have a duty to obey, and such decisions are often assumed to be lawful, even though their lawfulness may be contestable in an appeal procedure.
The same legality principle limits the competences of public authorities, by making them conditional upon statutory constraints and safeguards. Next to this, some jurisdictions have developed unwritten principles that have force of law, thus regulating how public authorities can use their competences. Such principles are often divided in substantive and procedural principles, for instance: the principles of trust and legitimate expectations, fair play, reasoned decisions, and proportionality as well as subsidiarity. These principles have been recognized and developed by courts with jurisdiction concerning actions and decisions based on administrative law. Such jurisdiction provides citizens with legal remedies against public authorities.
Legal remedies form a crucial safeguard in the context of administrative law, as they give citizens the competence to appeal against decisions of public authorities in a court of law. Such an appeal may or may not suspend the duty to comply with the decision and should e.g. enable the testing of the validity or applicability of the legal basis, as well as the manner in which the administration has used its competences. Imagine that the tax authorities decide that one’s income over 2017 is 120.000 euro, imposing the correlated income tax of e.g. 67.000 euros, whereas another interpretation of what constitutes one’s actual income results in an income of 110.000 euro. Without a system of legal remedies, one could maybe ask the tax authorities to revise the decision, but lack the right to present one’s position to an independent court. Once that court has decided, other tax payers have a more precise understanding of how one’s income should be calculated. So, the system of legal remedies in administrative law contributes to legal certainty.
Constitutional and administrative law are core to the Rule of Law; they vouch for the integrity of a government’s conduct versus its citizens. We should remind ourselves that limited government cannot be taken for granted. The idea that government must be brought under the Rule of Law, facing countervailing powers to reign in its potentially unlimited rule, is a historical artefact that must be reinvented and sustained.
Criminal law is usually divided into substantive law and procedural law. The first contains the primary rules (prohibitions) that delineate which actions qualify as criminal offences. In the Criminal Code, as discussed above, these primary rules are often hidden in secondary rules, e.g. ‘Whoever hacks into a computing system without right, can be punished with maximum 4 years of imprisonment and/or a fine of 20.000 euros’. Though this norm explicitly addresses the state, attributing the legal power to punish a person if specified conditions are satisfied, the norm indirectly addresses citizens by delineating a prohibited action as punishable.
Outside the Criminal Code, e.g. in Acts of Parliament that legislate on traffic, environmental or tax law, the primary norms are formulated separately. Here, separate secondary rules impose criminal or administrative sanctions, often situated at the end of the Act in a chapter on enforcement. Note that in many jurisdictions the administration does not have the legal power to criminalise unlawful behaviour, unless specifically authorised and conditioned in an Act of Parliament.
An example of a secondary rule that criminalises the violation of a separately formulated primary rule, would be art. 118(1)(a) of the UK Environmental Protection Act 1990 Chapter 43:3
118 (1) It is an offence for a person:
(a) to do anything in contravention of section 108(1) above in relation to something which is, and which he knows or has reason to believe is, a genetically modified organism;
This is the secondary norm by which the violation of a primary norm is criminalised. The relevant primary norm can be found in art. 108(1) of the same Act:
108.(1) Subject to subsections (2) and (7) below, no person shall import or acquire, release or market any genetically modified organisms unless, before doing that act
(a) he has carried out an assessment of any risks there are (by reference to the nature of the organisms and the manner in which he intends to keep them after their importation or acquisition or, as the case may be, to release or market them) of damage to the environment bemg caused as a result of doing that act; and
(b) in such cases and circumstances as may be prescribed, he has given the Secretary of State such notice of his intention of doing that act and such informatton as may be prescribed.
Substantive criminal law thus determines (1) which conduct is punishable, (2) with what punishment. To be punishable, conduct must at least be unlawful, but – as indicated above, this is not a sufficient condition (see figure 3). To be punishable the relevant conduct must be defined in a way that clarifies in a precise way when citizens become liable to punishment. Legal certainty requires that the scope of the offence must be transparent to those subject to the legal effect of criminalisation. Note that the legal effect is not punishment, but punishability.
Legal certainty is further enhanced and protected by the criminal law legality principle, which is even more stringent than the generic legality principle of public law. In criminal law, this principle is also called the lex certa principle that safeguards: (1) a reasonably precise formulation of criminal offences to prevent overinclusive criminalisation, and (2) protection against retroactive application. The latter entails that actions (including omissions) can only be punishable if they were criminalised when performed.
By way of example we will discuss a leading case of Dutch case law, under the heading of ‘Old style smart metering’, though it usually goes by the name of ‘the electricity judgment’.4
The facts of the case are quite simple: a dentist in The Hague repeatedly uses a knitting needle to halt the electricity meter, thus reducing his electricity bill. He is charged with theft and sentenced to three months of imprisonment. The criminal offence of theft is defined in art. 310 of the Netherlands Criminal Code (NCC):
Who takes away a good that belongs in whole or in part to another, with the intention to appropriate it unlawfully, will, as guilty of theft, be punished with imprisonment of at the most 4 years or a fine of the fourth category.
The legal effect that applies if the legal conditions are satisfied are: (1) that one is guilty of theft, and therefore punishable by way of an imprisonment of maximum 4 years, or a fine of fourth category. This legal effect depends on the following legal conditions:
a person has taken away
that belongs to another (in whole or in part)
with the intention to appropriate it
In this case, the dentist appealed to the Supreme Court, claiming that electricity is not a good, because it is not tangible. The Advocate-General (a formally appointed advisor to the Court) agreed and pointed out that other intangible goods such as intellectual goods cannot be stolen. The Supreme Court, however, decided that the term good should be understood to encompass electricity. It gave the following reasons for qualifying electricity as ‘a good’ in the sense of art. 310 NCC: it can be transferred, accumulated and kept in store; it has an economic value; it can be taken away and appropriated unlawfully (by using the knitting needle). In other words, the court stipulated the following criteria to qualify something as ‘a good’ in the sense of art. 310 NCC: (1) an independent existence, (2) transferability, (3) economic value, and (4) appropriation.
This case was a seminal case, because it seemed to reason by way of analogy: if money is a good, the same goes for electricity; if taking away another’s money without right is a criminal offence, the same goes for taking away another’s electricity. More abstractly, one could argue that the court said that since stealing a tangible good is punishable, stealing an intangible good is also punishable. This could have many consequences for the theft of other intangibles, such as intellectual property rights or other types of information.
In substantive criminal law, reasoning by way of analogy is prohibited. The reason is that this could extend the scope and the reach of the criminal law beyond what those subject to its legal effect legitimately expect. This is why the court went out of its way to clarify that its reasoning is not a matter of analogy, but of extensive interpretation. Instead of saying: ‘Since stealing a tangible good is punishable, stealing an intangible good is also punishable’, the court said: ‘The term “good” must be understood to include electricity, even if it does not include intangible goods’. To justify such extensive interpretation, the court provided a set of reasons that clarify that this interpretation is reasonable and fits the system and the purpose of the relevant law.
With the advent of digital data, the question of what qualifies as ‘a good’ in art. 310 NCC has returned many times. In the Netherlands, for instance, in cases about embezzlement of money from a bank account,5 ‘stealing’ data from another’s computing system,6 stealing money with a smartcard and password via an ATM,7 and ‘stealing’ bandwidth.8 In the latter case the court found that ‘taking’ bandwidth does not imply that others have less, suggesting this may nevertheless qualify as an offence under art. 138ab NCC (unlawful access to an ‘automated work’).
The Court of Appeal in The Hague tested this option,9 but concluded that since a router is not an ‘automated work’ art. 138ab NCC does not apply. This was based on art. Art. 80sexies NCC, which stated that:
An ‘automated work’ is to be understood as a device that is meant to store, process and transfer data electronically.
The court of appeal decided that a router is not an ‘automated work’ because it does not store, process and transfer data. This, in turn, was overturned by the Supreme Court,10 clarifying that a router is part of a networked computing system that can store, process and transfer data (thereby it is an ‘automated work’).
Moving deeper into the onlife world, two more key judgments offer an interpretation of ‘a good’ in the sense of art. 310 NCC. In 2012, when asked whether virtual goods (‘owned’ in an online game environment) can be stolen, the Supreme Court decided that, indeed, depending on the circumstances data can be qualified as a ‘good’ in the sense of 310 NCC.11 Also in 2012, when asked whether sms-messages and mobile phone minutes can be stolen, the Supreme Court confirmed that this is possible.12
We can now draw a nice timeline, specifying the legal conditions that must apply to qualify something as a ‘good’ in sense art. 310/326 NCC:
Independent existence (Electricity Judgment 1921)
Transferability (Electricity Judgment 1921)
Economic value (Electricity Judgment 1921)
Appropriation (Electricity Judgment 1921)
Function in societal intercourse (Money in a bank account Judgment 1982)
Loss of possession after transfer (Stealing data judgment, 1996)
These conditions have been applied in all subsequent judgments, highlighting that to qualify as a good it must be rivalrous (one person having more implies another person having less) as well as exclusivity (either the victim or the perpetrator has control over the good). These criteria will co-determine answers to new questions, such as, whether stealing a pin code via a brain interface qualifies as theft in the sense of art. 310 NCC, or as unlawful access to a computing system under art. 138ab NCC.
A similar case has been decided already in 1995, where the Supreme Court, applying the above criteria decided that a pin code in the mind of a person is not a ‘good’ in sense of 317 NCC (concerning extortion, blackmail).13 This was a first inkling that ‘loss of possession’ is a critical condition to qualify something as a good. So, what if we could actually remove a pin code from a person’s brain?
Back to why it matters whether a certain conduct does or does not fall within the scope of a criminal offense at the time of the conduct. Why prohibit retroactive criminalization and analogous reasoning, and why should extensive interpretation be limited? Because the legal effect of criminalization means that conduct becomes punishable, the invasive nature of punishment requires an enhanced degree of legal certainty (as discussed above this is called lex certa and aligns with the criminal law legality principle). At the end of the 18th century, the famous legal scholar Beccaria formulated this principles as a maxim for a legitimate criminal law: nullum crimen, nulla poena sine preavia lege poenali (no crime, no punishment without prior criminalisation).
One final example that may speak to a computer scientist. In a tweet, Ted Neward wrote:14 ‘Every. Single. Software developer. Must. Take. Note. YOU can go to jail for the code YOUR BOSS tells you to write’. He linked a news item about a Volkswagen engineer, who ‘helped develop the software that concealed high levels of pollutants generated by Volkswagen’s diesel engines’15 and who was subsequently sentenced to 40 months of prison. The sentence has been considered as harsh, because the engineer was not the mastermind of the deceptive scheme and merely seemed to have followed orders. The objective of the conviction was not only retribution, but clearly also deterrence, meant to warn off other engineers from following orders to commit a criminal offence. This raises many fascinating questions about the goals of legitimate public punishment, including the question of whether one offender may be used as an example to deter others and how this relates to justice and equal treatment if similar offenders are not prosecuted. Let us take note that it is not possible to prosecute each and every suspect of a criminal offence, while also raising a flag about the legitimacy of policies developed to make the right kind of choices about public prosecution.
The strict requirements surrounding the articulation of a criminal offence also concern potential justification and excuse. Even when a person commits the offence as defined, they may be able to justify their action. For instance, one may have killed another person intentionally, thus fulfilling the legal conditions of manslaughter, but nevertheless not be punishable because: (1) the act was justified by self-defence, having to prevent one’s own or another’s death or serious injury, or (2) the act must be excused because the situation caused such immanent psychological stress that one cannot be considered guilty for having killed e.g. thief who nevertheless did not threaten one’s or another’s life. Though justification and excuse cannot be taken lightly and will require serious argumentation, to be convicted for a criminal offence, its wrongfulness and the culpability of the perpetrator must be confirmed.
This leads to a quadruple structure of a criminal offence, in other words, the legal effect of punishability is conditional on the following legal conditions:
Actus reus (the act and its qualification)
an action (in criminal procedure this relate to the law of evidence)
that falls within the scope of a criminal offence (in criminal procedure this regards the qualification of conduct as a criminal offence)
Mens rea (the elements):
wrongfulness (in criminal procedure this regards the defence of justification)
culpability (in criminal procedure this regards the defence of disculpation or excuse)
As indicated, the structure of the criminal offence is deeply entwined with criminal procedure, notably with the questions a court must answer before convicting a defendant. The legal effect of a conviction thus depends on all of the following questions being answered positively (the conditions are cumulative).
The conduct that is charged must be proven beyond reasonable doubt. Defence: ‘I did not do it’.
The proven conduct must qualify as a criminal offense (legality principle).
Defence: ‘the proven conduct is not a criminal offence’.
The action was wrongful (no justification).
Defence: ‘I had a ground for justification’ (e.g. permission).
The defendant was culpable (no excuse).
Defence: ‘I had an excuse’ (e.g. psychiatric disorder).
In the case law about whether data, bandwidth or virtual goods qualify as ‘a good’ in the sense of art. 310 NCC, the second question was at stake.
Criminal procedure concerns both pretrial police investigations and the trial itself. The legality principle that informs government competences under public law also applies to the competences of police, public prosecutor and the courts when deciding criminal cases. Due to the impact of punishment and the invasive character of criminal investigation, legality issues in criminal procedure are core to the legitimacy of criminal investigation, prosecution and conviction.
In the context of criminal procedure, the term ‘legality principle’ is also used to denote a strict form of legality, referring to the idea that all criminal conduct should be prosecuted. This interpretation of the legality principle is opposed to the idea that the public prosecutor has discretion when deciding whether or not to prosecute. In the Netherlands, for instance, this discretion is codified in the Code of Criminal Procedure (NCCP), stating that the prosecutor may abstain from prosecution based on the general interest.16 Case law has clarified that the office of the public prosecutor must develop a policy, specifying the criteria that are used to determine whether or not to prosecute. Examples can be found in the Dutch policies around euthanasia and the possession of soft drugs. In both cases the relevant actions (a doctor performing euthanasia or a person walking around with soft drugs) remain criminal offences, but the office of the public prosecutor has developed and published policy rules that detail under what conditions a doctor or a soft drug user will not be prosecuted. Legal certainty not only demands that citizens can foresee which of their conduct is punishable, but can also foresee under what conditions they will be prosecuted. The difference between (1) a strict legality principle that requires prosecution of all alleged criminal offenses and (2) a principle of discretion that makes room for policy considerations connects with different justifications of punishment. Some theories highlight that punishment is retribution for the violation of norms that must be upheld in the general interest, even if no concrete, identifiable damage has been caused. This would rule out any discretion to abstain from prosecution. Other theories highlight that punishment is meant to prevent further crime, both by way of deterring others from committing similar offences and by way of preventing the convicted offender from re-offending. Most jurisdictions are based on a combination of retribution and prevention; the public prosecutor must develop and publish its policies to clarify how discretion will be exercised. Without such policy the decision to prosecute could be arbitrary, depending on private considerations of whoever holds the office of the public prosecutor instead of justifiable choices with regard to the public interest. Note that in practice it is not even remotely possible to prosecute all criminal offences. Acknowledging this and being transparent about the foreseen use of discretionary competences form important legal safeguards against arbitrary punishment.
In Europe a criminal charge results in the applicability of the right to a fair trial, as articulated in art. 6 of the European Convention of Human Rights (ECHR):
1. In the determination of his civil rights and obligations or of any criminal charge against him, everyone is entitled to a fair and public hearing within a reasonable time by an independent and impartial tribunal established by law. Judgment shall be pronounced publicly but (…).
2. Everyone charged with a criminal offence shall be presumed innocent until proved guilty according to law.
3. Everyone charged with a criminal offence has the following minimum rights:
(a) to be informed promptly, in a language which he understands and in detail, of the nature and cause of the accusation against him;
(b) to have adequate time and facilities for the preparation of his defence;
(c) to defend himself in person or through legal assistance of his own choosing or, if he has not sufficient means to pay for legal assistance, to be given it free when the interests of justice so require;
(d) to examine or have examined witnesses against him and to obtain the attendance and examination of witnesses on his behalf under the same conditions as witnesses against him;
(e) to have the free assistance of an interpreter if he cannot understand or speak the language used in court.
We can detect six fair trial principles that underlie this right: (1) the presumption of innocence, (2) the right to an independent and impartial tribunal, (3) equality of arms between public prosecutor and defendant, including internal publicity, (4) immediacy of the presentation and testing of the evidence in court, (5) external publicity, and, (6) the right to have a final decision within a reasonable time. Taken together, these rights ensure that a defendant has the means to contest the lawfulness of police investigations and the evidence presented by the prosecution, including witness testimony. They also make sure that in principle the burden of proof is on the public prosecutor and until guilt has been established the defendant is not to be treated as if he is a perpetrator. This means that all measures taken before a conviction must serve other purposes than punishment, they may not be deterrent or punitive. Together these requirements condition lawful investigations and prosecution, and a valid conviction. They have generated a steady flow of case law of the European Court of Human Rights (ECtHR) that has jurisdiction to hear individual complaints of citizens of the Contracting Parties of the Council of Europe that instigated the ECHR.
This case law has, for instance, determined that the term ‘criminal charge’ has an autonomous meaning which does not depend on what a state defines as punitive sanctions. States therefore cannot disable the applicability of art. 6 ECHR by re-naming criminal offences as ‘regulatory offences’. If they choose to do this, art. 6 ECHR nevertheless applies if (1) the nature of the offence and (2) the severity of the penalty bring the offence within the bounds of the concept of ‘a criminal charge’. This will depend e.g. on whether the sanctions have punitive and/or deterrent objectives, or on whether other Contracting Parties qualify the offence as a criminal offence.17 Other case law determined that defendants must have access to and be able to challenge all and any evidence presented to the court, even if the public prosecutor wishes to hide information on grounds of public interest.18 More recently, the ECtHR decided that suspects that are interrogated by the police have a right to legal counsel.19
Though we did not discuss private law procedure it makes sense to say a few words at his point about private law procedure as compared to the criminal trial. First, let’s take note that the right to a fair trial (art. 6(1)) also applies to the determination of a person’s civil rights and obligations, wheras 6(2) and (3) are reserved for a criminal charge. Second, in private law proceedings, the default rule is that whoever initiates proceedings bears the burden of proof. Think of requesting a court order to comply with contractual obligations, an injunction to stop unlawful conduct or compensation for damage caused by a breach of contract or a tort. In case of liability for high risk conduct, the burden of proof is sometimes inversed, while risk liability and strict liability may further diminish the burden for the plaintiff. Think of the use of asbestos or other pollutants by the industry, which have been proven to cause grave health problems, or safety hazards in employment situations. Legislatures and courts thus aim to provide effective protection for victims, especially when causality can be inferred at a statistical level (increased probability to suffer harm or damage), but not determined at the individual level (where e.g. other causes may have contributed to the damage). In the criminal trial, the public prosecutor bears the burden of proof, as part of the presumption of innocence (art. 6(2)). Third, whereas the same presumption demands that in criminal procedure the standard of proof is ‘beyond reasonable doubt’, in private law the standard is usually much lower, e.g. clear-and-convincing evidence or even preponderance of evidence. Plausibility is often considered enough. Fourth, if the defendant in private law proceedings does not contest the evidence, the plaintiff’s request must normally be granted. This goes back to the idea that within private law, parties are treated as autonomous and equal persons, capable of deciding amongst themselves the scope and the shape of the conflict. Such party autonomy does not exist in the criminal law, where imposing punishment on an innocent person is to be avoided even if defendant and prosecutor were to strike a deal. Since criminal law attributes the state with a number of invasive legal powers, a more active position of the court is warranted when it comes to deciding the reliability and the relevance of the evidence and its contribution to proving the offence ‘beyond reasonable doubt’. In the criminal trial the defendant and public prosecutor are not considered equal, calling for a set of compensatory rights to provide the defendant with effective means to defend themselves.
For a general but more detailed introduction to private law:
Hage, Jaap, Antonia Waltermann, and Bram Akkermans, eds. 2017. Introduction to Law. 2nd ed. 2017 edition. New York, NY: Springer, chapter 3 (conceptual distinctions), 4 (contract law), 5 (property law), 6 (tort law).
On the legal order as a system of legal relationships and the concept of individual rights:
Achterberg, Norbert. 1982. Die Rechtsordnung als Rechtsverhältnisordnung: Grundlegung der Rechtsverhältnistheorie. Berlin: Duncker & Humblot.
Edmundson, William A. 2012. An Introduction to Rights. 2nd ed. Cambridge University Press.
For a comparative perspective on tort law, notably the unwritten duty of care:
Van Maanen, Gerrit, David Townend, and Almaz Teffera. 2008. ‘The Dutch ‘Cellar Hatch’ Judgment as a Landmark Case for Tort Law in Europe: A Brief Comparison with English, French and German Law with a ‘Law and Economics Flavour’. European Review of Private Law 16 (5): 871–89.
On common principles and rules of European private law:
Bar, Christian von, and Eric Clive, eds. 2010. Principles, Definitions and Model Rules of European Private Law: Draft Common Frame of Reference. Oxford University Press, USA.
More specifically European comparative property law:
Erp, Sjef Van. 2006. ‘Comparative Property Law’. The Oxford Handbook of Comparative Law, November. https://doi.org/10.1093/oxfordhb/9780199296064.013.0033.
More specifically European contract law:
Kötz, Hein. 2017. European Contract Law. New Edition, Second Edition. Oxford, New York: Oxford University Press.
On fundamental principles of private law from a constitutional theory perspective:
Mak, Chantal. 2012. ‘Europe-Building Through Private Law: Lessons from Constitutional Theory’. SSRN Scholarly Paper ID 2023141. Rochester, NY: Social Science Research Network. https://papers.ssrn.com/abstract=2023141.
For an in-depth understanding of the freedom to act strategically in the private sphere:
Habermas, Jürgen. 1996. Between Facts and Norms: Contributions to a Discourse Theory of Law and Democracy. Studies in Contemporary German Social Thought. Cambridge, Mass.: MIT Press.
A general but detailed introduction to constitutional, administrative and international public law:
Hage, Jaap, Antonia Waltermann, and Bram Akkermans, eds. 2017. Introduction to Law. 2nd ed. 2017 edition. New York, NY: Springer, chapters 8 (constitutional law), 9 (administrative law) and 12 (international law).
On constitutional law:
Frankenberg, Günter. 2012. ‘Comparative constitutional law’. In The Cambridge Companion to Comparative Law, edited by Mauro Bussani and Ugo Mattei, 171-190. Cambridge: Cambridge University Press.
Waluchow, Wil. 2018. ‘Constitutionalism’. In The Stanford Encyclopedia of Philosophy, edited by Edward N. Zalta, Spring 2018. Metaphysics Research Lab, Stanford University. https://plato.stanford.edu/archives/spr2018/entries/constitutionalism/.
On administrative law:
Bignami, Francesca. 2012. ‘Comparative Administrative Law’. In The Cambridge Companion to Comparative Law, edited by Mauro Bussani and Ugo Mattei, 145–70. Cambridge University Press.
Stroink, F., and E. Van der Linden, eds. 2005. Judicial Lawmaking and Administrative Law. Antwerpen : Maastricht: Intersentia.
A general but detailed introduction to criminal law:
Hage, Jaap, Antonia Waltermann, and Bram Akkermans, eds. 2017. Introduction to Law. 2nd ed. 2017 edition. New York, NY: Springer, chapter 7
Horder, Jeremy. 2016. Ashworth’s Principles of Criminal Law. 8 edition. Oxford, United Kingdom: OUP Oxford.
A discussion of the legality principle in the context of European Criminal Law:
Peristeridou, Christina. 2015. The Principle of Legality in European Criminal Law. Cambridge, UK: Intersentia.
Guidance on the right to a fair trial:
European Court of Human Rights (ECHR), Guide on Article 6 of the European Convention on Human Rights. Right to a fair trial (criminal limb), 2014, available at https://www.echr.coe.int/Pages/home.aspx?p=caselaw/analysis/guides&c=#