The article is devoted to the problems of seizure and its efficiency. Variants of content sources of evidence are considered. The decision on the seizure must be justified by evidence. Objects relevant to the criminal case, but received by non-procedural way, may lead to examining as witnesses people who carried out these actions. It is proved that the evidence is used as a factual ground for executing seizure in three variants: 1) the only evidence; 2) cumulative evidence; 3) the combination of evidence and non-procedural data. The author stresses the importance of the guarantee of rights and freedoms of people involved in the seizure. It is argued that non-procedural information is used to justify the seizure by the use of: a) the only source of non-procedural data; b) the aggregate non-procedural data. The author pays a special attention to the proposals directed at the improvement of the seizure. He has discovered the factors reducing its efficiency. The scientific results are supported by a significant amount of empirical evidence.