Annotation: The article considers the concept of human rights and freedoms through the prism of covering the essential characteristics of mechanisms for ensuring the rights and fundamental freedoms of human and citizen. The author analyzed the current legal and regulatory framework at the national and international levels, on the basis of which were made conclusions about the perfection of existing on the perfection of the levers of guarantee, protection and protection of human and citizen's rights and freedoms in the context of the exercise of law enforcement functions and activities, which are aimed at the protection by the state authorities sovereignty, territorial integrity and national security in Ukraine. Also the author considered basic principles of the activity of the Security Service of Ukraine, as a state special purpose body with law enforcement functions, and their influence on the formulation and implementation of policies in the field of custody and protection of human and citizen's rights and freedoms. The scientists covered the ideas of the primacy of human and citizen in the modern law-based and social state, that's why guaranteeing a qualitative and effective regulation of the implementation of constitutional rights and freedoms are very important part of rule-making and management activities of public authorities, especially with regard to the security sector, because this link is the most vulnerable in terms of admitting the violation of rights and freedoms by officials. The article also explored the issue of liability for violations of the rights and fundamental freedoms guaranteed by the Constitution of the individual and the citizen in the context of law enforcement activities in Ukraine.