During the current and the previous two to three decades the volume of norms of national and international law regulating the field of security has grown evidently. In the Republic of Serbia alone there are around 300 laws and by-laws in force in this field. Despite the fact, domestic jurisprudence still does not show enough interest for a more comprehensive theoretical analysis of security issues. Some initial difficulties in that respect certainly lie in dilemmas concerning the theoretical scope of the complex concept of security. That motivated the author to offer his own contribution to the determination of this concept in legal theory. In the first part of the article, the author briefly points out the etymology of the general concept of security, the semantic issues and the historical development of theoretical foundation of the state's security function. This is followed by a more thorough analysis of modern legal aspects and determinants of the concept of security. Finally, a conclusion is drawn on the legal determination of the concept of security. The central part of the article deals with the legal analysis of the narrower concepts of individual, national and international security, as well as their mutual conditionality. The author specifically points out the legal vagueness of the concept of human security and difficulties of legal scope of global security. Even though these concepts are highly appealing, human and global security are at the same time concepts eligible for abuse, as they can be used as instruments of the policy of power in a unipolar world. According to the author, there are at least four important aspects which complicate the determination of a more general concept of security which is of importance for the law. These aspects refer to (1) the ambiguity of this concept and its different legal use, (2) its constant evolution, (3) the constant broadening of the list of values which are to be protected on one side and the list of challenges, risks and threats to security on the other side, as well as to (4) the ideological content which is intensively introduced to the discussion on security and the laws regulating the field of security. As an initial definition of the concept of security which is of importance to the law, the author offers the following definition: In legal terms, security is the condition of absence of danger projected by the law and secured by the state by the legally regulated activity of its bodies and other subjects. Dangers relevant to security should have a certain level of significance, their own form of manifestation and the eligibility to endanger security and not to be abstract or quite insignificant. Such dangers are significant to the law only when they endanger the values determined in strategic documents and protected by the constitution and laws.