The author notes that the lex, which is an external form of expression of law, must be expressed and approved in its source in an appropriate and formal way, and it is not the only one in the system of sources of law. The main types of effective law are determined on the basis of certain methods of forming its sources. As an integral part of law, it exists in most sources of the legal systems of modern states and governs these sources, that is, the lex is the first source of law. 

The ongoing integration processes in the world further strengthen the role of international law, penetrating into the space of international treaties and the hierarchy of sources of domestic law. In conclusion, it is said that one of the most important issues in Azerbaijan is the resolution of the issue of compliance of international treaties and agreements with the Constitution of the country.