The filtration camps (PFL; until February 20, 1945 - special camps), special institutions that existed in the USSR in 1942-1948 for the maintenance of groups of persons who were considered by the authorities as politically unreliable. Initially created for the so-called. filtration (checking) of former prisoners of war and "encirclement". In the future, they were also used for the temporary detention of civilians and ordinary collaborators. They were subordinate to the structures of the NKVD-MVD of the USSR. In total, from January 1942 to March 1946, 82 PFL and independent camp departments were created, at least 653 thousand people passed through them. Filtration in the PFL was carried out by special departments of the NKVD, from April 1943 - by departments of SMERSH. PFL were part of the forced labor system of the USSR. Most of those who entered the PFL were not arrested as a result of the check. In 1995, all those who went through the PFL, with the exception of collaborators, were recognized as victims of political repression.