Ex post facto

Ex post facto — «обратная сила закона» — is used to refer to a law that applies retroactively. In Russia, criminal law can apply retrospectively if it decriminalises a conduct or mitigates a punishment; it cannot criminalize an act that was legal when originally performed nor can it retrospectively worsen a penalty (art. 10 of the Criminal Code). The Russian Constitution contains general prohibition on ex post facto laws introducing or aggravating responsibility (art. 54 of the Constitution).

This is an old and well established principle of Russian and, before that, Soviet law. However, there is at least on case when this principle was broken. In 1961, Rokotov, Faibishenko and Yakovlev were executed for illegal dealing in foreign currency. At the time the maximum penalty for this crime was eight years imprisonment (art. 88 of the Criminal Code of the RSFSR). Yet, the new law was adopted with retrospective effect providing the death penalty, and the three were shot.

As far as civil legislation is concerned, it can have retroactive force, but as a general rule new laws apply to relations that have arisen after a new law came into effect (art. 4 of the Civil Code).