Abstract: This study is devoted to the research of an interbranch institute mercy which is also determined in the legislation of many Foreign countries. An ambiguous attitude of scholars to this institution is noted. Ch. Beccaria, I. Kant, N.S. Tagantsev and others are among the opponents of mercy. Modern researchers of this institute are not opposed to mercy but they emphasize the existence of serious competition from the institute of parole and the presence of regulatory framework gaps that provide this institution. This study emphasizes that the unification of the regulatory framework demands not only the improvement of Criminal Law enforcement procedural rules but also the adoption of the Federal Law “About amnesty in Russia”, taking into account international experience. We analyzed the issue of the humanism principle limits during the legal activities implementing rights. We talk not about dehumanization and the abolition of humanism principle. The thing is about the limits of humanity. With regard to the persons sentenced to imprisonment the principle of humanism is taken into account twice at the appointment and the execution of punishment and in the case sentenced to death, it is not considered at all. In relation with this, we offer to realize mercy for the purposes of justice in Russia only for the persons sentenced to the death as it is stated in the International Covenant “On Civil and Political Rights” issued on 16th December 1996.