One of the key definitions used in legal science is the term "source of law". At all times, he undergoes thorough study in the framework of both general theory and industry disciplines. 
General classification
Currently, there are four legal sources:
- Custom.
- Legal act.
- Precedent.
- Regulatory agreement.
One of the central places in science is a legal precedent. As a source of law, it has been known since ancient times. This is what largely determines the increased interest in this phenomenon. Consider in more detail the concept of "legal precedent."
History reference
Legal precedent as a source of law was widely used in ancient Rome. Practical cases formed the basis of the first legislative collections. Legal precedents were decisions in certain cases of praetors and other masters. Initially, they had the power to handle disputes only for those persons with whom they were accepted, and only for a specified period. Over time, the most successful cases have become sustainable. Gradually, a system of generally binding norms was formed from them, called praetorian law. The occurrence of this phenomenon is due to the peculiarities of the formation of the doctrine in antiquity. One of them is the casual nature of the acts, when the lawmaker tried in the norm to foresee all possible life situations. Today, legal precedent in many countries is the only way to resolve disputes, playing a dominant role in doctrine. 
Main categories
In modern science, administrative and judicial precedents are distinguished. The difference between them is due to the presence in the state structure of the relevant bodies. In some countries, these types of legal precedents are very widespread and fairly well formed. Administrative practice is the activity of numerous government agencies in addressing the challenges facing them. The judicial system exists in countries independently of other branches of government.
Administrative practice
Legal precedent may be the decision of the executive body in a particular case. In modern theory, the question of administrative practice of this nature is poorly developed. There is not much information about this phenomenon, as, for example, about judicial precedents. The latter are often covered and discussed in relevant circles. In general, an administrative legal precedent is considered as the behavior of an official, a state body, which was at least once and can act as a model in similar circumstances. In practice, however, the phenomenon under consideration is usually not associated with the activities of representatives of the executive branch. 
Legal case law
It represents the decision of the authorized body in a particular civil or criminal case. The adoption of such acts is the responsibility of the courts. Such a decision will be deemed binding on instances of the same level or standing below when resolving a similar dispute. The legal precedent in this case is an exemplary model for the interpretation of a law. Thus, the authorized instance acts as a legislative body. Such activities are qualified in two ways.In the first case, the court confirms the existence of a law-making function, and in the second it is argued that it does not create laws, but only formulates norms. Today, such decisions are at the heart of the Anglo-Saxon doctrine, which is used in the UK, USA, India, New Zealand, Australia, Canada and so on.
The legal precedent is based on the principle that the authorized body cannot refuse to resolve a dispute to someone in the absence of a suitable rule of law. Instance is obliged to make a decision on the case. In this case, it is worth emphasizing that a precedent can be created only by the highest judicial body of the state. 
Structure
Among lawyers, there is currently no unity regarding the composition of the precedent. Nevertheless, in practice one can single out the most popular approach to this issue. In accordance with it, legal precedent includes:
- Ratiodecidendi is the essential solution. That is, this is the rule itself, which forms the norm.
- Obiterdictum - "incidentally said." Under it should be understood other circumstances of the case that justify the decision.
The authorized person who resolves the dispute does not establish which element is primary and which is additional. This is the competence of another (higher) employee who determines whether this decision can act as a legal precedent or not. 
Ratiodecidendi
In practice, there is no single interpretation of this definition and no method has been devised to isolate this element from the solution. In the relevant publications there is an opinion that this term can be used in two meanings:
- As a legal norm proposed by a judge and used as the basis of his final decision.
- As a circumstance in the presence of which the act acquires a binding character.
Luelman proposed distinguishing from the concept of "a legal basis that meets the version of the court" and "a true basis - such as it will be presented in another instance." Professor Cross regarded the ratiodecidendi as a norm, indirectly or directly interpreted by an authorized person, as a necessary step in achieving his version or as an obligatory part of the instructions by a jury. Professor Goodhart defined the term as relevant facts in conjunction with a decision based on them.
Despite certain differences in the above interpretations, they all reflect the importance that is given in practice to the ratiodecidendi. This element is the main part of the decision, expressing the norm and giving the act a binding character. In the future, the adopted regulation will have to be followed by all lower courts and instances located at the same level as the one that delivered it. 
Domestic practice
In Russia, the provisions of the Romano-Germanic doctrine are used. This means that a normative act acts as a source of domestic law. It can be in the form of an international treaty, federal law, the Constitution, and so on. Judicial decisions are not recognized as normative acts. In this regard, they cannot form certain provisions. Thus, legal precedent is alien to domestic practice. Only regulatory acts play a role in regulating civil relations. Their action is mandatory for all subjects. The court decision, in turn, is an individual act. It is aimed at specific individuals who participated in the consideration of a particular case. Thus, a court decision in Russia acts as a law enforcement, interpretation of the law.
The tasks of the authorized authority include the analysis of existing provisions. Based on the current legislation, an appropriate decision is made. In general, the court cannot create a new norm. As an exception, however, acts of the Constitutional Court on the recognition of the unconstitutionality of certain legislative provisions or the entire normative act are made.