Abstract: The research subject covers particular legal problems of using the results of investigative operations, restricting constitutional rights of citizens, in criminal proceedings. Legislation on investigating operations establishes obligatory conditions for the conduction of such investigating operations, consisting in the data on the illegal act, which is being prepared, is being committed or has been committed, and which must be preceded by pre-trial investigation. Within investigative actions, preliminary qualification of deeds is based upon the materials, acquired during investigative operations and evaluated mainly subjectively, and therefore, can lead to mistakes and inaccuracies in the evaluation of illegal acts and establishment of compositions of crimes. In this context comes up the problem of objectivity of data and its sufficiency for court sanctioning. The research methodology is based on modern achievements in epistemology. The author applies theoretical and general philosophical methods (dialectics, the system method, analysis, synthesis, analogy, deduction, observation and modeling), traditional methods of jurisprudence (formal logical) and the methods of sociological research (expert assessment, etc.). Based on the analysis of law-making regulations and concepts, the author offers the way of using the results of investigative operations, restricting constitutional rights of citizens, in the context of transformation of qualification of illegal deeds and, consequently, transformation of the form of pre-trial investigation.