Based on the principle of legality, administrative law requires that acts and decisions of public authorities have a legal basis. This legal basis is their responsibility, for example for road maintenance, decision-making on individual taxes or social security and the imposition of political rules on industry regarding certain pollution levels (emission limits). The citizens affected by the decisions are required to obey, and these decisions are often considered lawful, even if their legality can be challenged in an appeal procedure. Remedies are an essential guarantee under administrative law, as they give citizens the power to appeal decisions taken by public authorities to the courts. Such an appeal may or may not suspend the obligation to comply with the decision and should, for example: make it possible to verify the validity or applicability of the legal basis and the manner in which the administration has exercised its powers. Imagine that the tax authorities decide that income above 2017 is €120,000 and levy correlated income tax of €67,000, for example, while another interpretation of what constitutes actual income gives income of €110,000. Without an appeal system, you might be able to ask the tax authority to review the decision, but you do not have the right to present your point of view before an independent tribunal. Once this court renders its decision, other taxpayers will have a more accurate understanding of how income should be calculated. The system of administrative law remedies thus contributes to legal certainty. The purpose of public law is the public interest or public good, Latin la res publica, which led to the idea of a republic. The public interest has a very broad meaning and requires, in principle, an assessment of a diversity of public interests that may be incompatible in particular situations. Public law concerns, for example, safety, welfare, public health, care for the elderly, public education, management of public transport, full employment, social housing, etc.

Public law, especially administrative law, is limited by the principle of legality, which requires a legal basis for all acts and decisions of the Government. This legal basis may be very general if the acts or decisions do not have negative consequences, but if negative effects are to be expected, the legal basis must be specific, what it allows, for what purpose and under what precise conditions. For example, if the government wants to refuse a person to allow the construction of a new highway, very specific conditions apply, and the person must be compensated. The principle of legality requires that the government always act within the limits set by the written or unwritten constitution (which confers powers on the government). This is directly related to the fact that the legal norms of the rule of law are both constitutive and restrictive of the legal powers they confer on them (see Chapter 2). In addition, international human rights law and other treaties to which a state is bound will further limit the powers of government. Note that these conditions are cumulative. All conditions must be met. We will now check if ownership of the book will be transferred. For a delivery, it would be enough for Alice to give the book to Bob. If Alice has entered into a valid sales contract with Bob, there is a valid legal basis or title.

However, since Alice is not the owner, she lacks availability. One of the crucial legal powers that the law assigns to property is the power of disposition or freedom to share, sell, give away or even destroy the object of property. It seems that Alice cannot transfer ownership because she has no power of disposition. A legal object is an entity that is the subject of a specific legal relationship between legal entities. Think of a legal asset such as an intellectual property right, a material obligation, or a specific obligation. If I sign a contract with one of my students to sell her a book, the book is the legal object. More precisely, the right of ownership is the legal object that is transferred. Domain, in Anglo-American law, the absolute and complete ownership of the land or the land itself which is thus owned. The estate is the most complete and superior land ownership. The domain as a legal concept derives from the dominium of Roman law, which included both the right of property and the right to own or use property.

The adoption of Dominium by English common law was not complete and omitted some of the finer distinctions developed by Roman law. In private law, there are only a limited number of absolute rights, which is linked to the fact that everyone was obliged not to interfere with these rights. In most jurisdictions, this set of property rights includes: ownership, land, lease, easement, superficiality, housing, usufruct, pledge and mortgage, and intellectual property rights (e.g., copyright, patent). We are talking about a closed system of property rights, since new rights cannot be created at will by individual legal entities, even if they agree. If the reader wishes to know more about the content of these rights (their legal conditions and the resulting legal effect), it is recommended to read the relevant literature (under the references of this chapter). This means that the law requires that 3 legal conditions be met to obtain the legal effect of a transfer of movable property: To return to the perspective of law as a complex architecture of legal relations between legal persons, we can present public law as follows: On the one hand, public law considers the legal relations between a State (as such) and its citizens, and, on the other hand, legal relations between States. The first concerns constitutional and administrative law, the second public international law. Constitutional law and international law have many dependencies, firstly because the Constitution determines whether, to what extent and under what conditions international law prevails over domestic law in the event of a conflict between the two. Second, international law can establish its own primacy, as in the case of jus cogens, i.e. law that applies to all States without exception (e.g. the prohibition of crimes against humanity and genocide).

Private law contains the rules of law that govern relations between legal persons at a horizontal level, thus excluding the government acting „as such“. Horizontal does not mean that entities are equal in the sense that they have the same economic or other power. This means that they are formally considered equal and are able to determine their own position in the law; For example, they may enter into contracts, sell their property and be held liable for unlawful misconduct. As mentioned above, private law respects the autonomy of individuals, but also contributes to that autonomy by allowing them to act strategically in the private sphere, as long as they act within the limits of the law. Other ways of contributing to individual autonomy can be seen, for example, in consumer and competition law, where they aim to compensate weaker parties with less bargaining power. We will now turn to real estate law, contract law and tort law. To illustrate the difference between private, public and criminal law, we will add a complementary perspective to shape the law. In addition to describing law as a unit of primary and secondary rules and underlying principles, we will introduce law as a system of legal relations between legal entities in relation to legal objects.