Retroactivity of the law in contractual relationships

Special features of the retroactivity of the law in contractual legal relations are researched, the retroactivity of the law is considered an exception to the general principle of the invariability of contractual conditions and the stability of contractual relations. The retroactive effect of the law aimed on an already concluded contract can be established in the law or some other regulatory legal act and is usually due to public and social tasks. A critical analysis of the legal and technical formula of the retroactivity “the effect of the new law applies to relations arising from previously concluded agreements" is carried out. The conclusion is made about the legal uncertainty and obscurity of such a formula, which brings along various law enforcement approaches and interpretations. It is proposed to use the following formula as a general rule for the retroactivity of a law in contract law: “if a new law is given retroactive effect, then when considering any disputes from previously concluded contracts, the new law should be guided, otherwise it should be directly and unambiguously provided by law”.