AT h. 1 tbsp. 10 of the Criminal Code the condition is fixed under which the criminal law is vested with retroactive force. In other words, it applies to actions committed before its adoption. Consider the features application of Art. 10 of the Criminal Code. 
General information
According to Art. 10 of the Criminal Code, if the law softens the sanction, eliminates the crime of the deed, improves the situation of the subject who committed the violation, he is endowed with retroactive force. Its provisions apply to citizens involved in the corresponding crime, before its entry into force. They include, among others, persons who are serving a sentence or have already served it, but their criminal record has not been withdrawn.
If the law establishes the crime of the deed, strengthens the sanction, worsens the position of a citizen, he does not have retroactive effect.
As establishes part 2 of article 10, if the provisions of the law mitigate the punishment that a person is serving, then it should be reduced to the extent established by the new legal act. 
Art. 10 of the Criminal Code with comments
The retroactive effect of a legal act is considered an exception to the rule on the operation of the law in time. The existence of such a norm is one of the manifestations of humanism.
Application of Art. 10 CC it is possible if the perpetrator commits an act under the action of one law, and is brought to justice under another legal act.
If the provisions of the latter are aimed at improving the situation of the subject, judicial and investigative officers should apply them. Moreover, the time of the act does not matter.
For example, after the introduction of the new Criminal Code in 1996, some acts were decriminalized. In particular, liability was not provided for failure to report a crime, violation of the order of departure, residence in the border zone, wrecking, and so on. 
Exceptions
The legal status of the subject, according to Art. 10 of the Criminal Code, cannot worsen if, after a crime committed by him, a new law was enacted enforcing a tougher sentence. In such situations, the previous normative act in force at the time of the act applies. So, the provisions of the previous Code on violation of personal privacy, illegal receipt of credit funds, illegal actions in the event of bankruptcy in respect of crimes committed before 01.01.1997 do not have retroactive effect. This is due to the fact that the 1960 law did not fix the punishment for these deeds.
Elimination of crime
In the provisions of Art. 10 of the Criminal Code uses several specific concepts. One of them is the elimination of crime.
A law decriminalizing an infringement is such a legal act under which an act previously a crime ceases to be so. It is transferred to the category of disciplinary, administrative, immoral, civil misconduct, or is not mentioned at all or encouraged by legal norms. 
The provisions of the law eliminating the crime of the deed may exclude from the Criminal Code the article establishing the punishment for it, change the disposition of the norm, introduce new elements into it, only in the presence of which the subject can be held accountable.
In addition, decriminalization can be carried out by introducing new rules into the General part of the Criminal Code. For example, they can establish previously unknown or expand traditional conditions that exclude crime. The rules may also provide grounds for exempting a person from liability not previously enshrined in law.
Commutation of punishment
In 1996, for the first time, the following were indicated as mitigating factors in the new Criminal Code:
- Reasonable risk.
- Execution of an order / order.
- Coercion (mental / physical).
Punishment can be mitigated by lowering the minimum, maximum, or both of these limits. The softer laws are:
- Not changing the limits of the main sanction, but excluding the mandatory imposition of additional punishment or imposing it, but in a milder form.
- Changing downwards the limits of punishments provided for by the Special Part.
- Providing for the possibility of the court at its discretion to impose an additional sanction, in contrast to the previously existing rules, which enshrined the obligatoriness of its imputation.
The procedure for the application of such normative acts secures Part 2 Art. 10 CC. 
Controversial moment
Discussions are ongoing in the legal literature about which law should include an act that mitigates and toughens the punishment at the same time. This, in particular, refers to provisions that reduce the minimum amount of the main or additional sanction and at the same time increase the maximum limit or act on the contrary.
In practice, the following approach is used. If a softer measure can be assigned under the new legal act, then it has retroactive force in the part that improves the position of a citizen. Those provisions that tighten liability are not subject to application, and the sanction is imposed on a citizen according to a previous law. 
Consider an example. Suppose, the previous law established for the act of 5-8 years in prison. In the new regulatory act, the sanction was changed to 3-10 years. Thus, the court received an abstract opportunity to deprive the subject of freedom for less than 5 years, that is, to soften the sanction, or to impose all 10 years, i.e., to tighten liability.
However, as established by Art. 10, the deterioration of the position of a citizen is not allowed, since it contradicts the principles of humanism of the law. Accordingly, the retroactive effect of the aforementioned normative act is valid only in the part mitigating liability, i.e., the court has the right to impute to the offender at least 3, but not more than 8 years in prison.
Additionally
Separately, it is worth mentioning the retroactive effect of the "intermediate" laws. This is the name of the acts that are in force after the softening of the previous law, but before the tightening of the new. 
For example, at the time of the crime, a sanction was imposed for him up to 6 years in prison, when bringing the guilty citizen to justice - up to 5, and at the time the court makes the decision - up to 7. Based on the principle of humanism, the court should apply an “intermediate” normative act as the most liberal, improving the position of the subject.