The relevance of the study is determined by the dynamics of development of inheritance law, both in general and its individual institutions, in particular, the institution of inheritance by will. Due to changes in Russian legislation, it is advisable to conduct a comparative legal analysis of the provisions on free will and the limits of its restriction to Russia and the United States. This will make it possible to determine the potential of the institution under study, used by various legal systems, to indicate direction of its further development in Russia. The leading research approach includes such scientific methods as dialectics, analysis, synthesis, deduction, comparative legal and formal legal method. Conclusions: The scientific approaches to understanding and restraining free will provided by US law differ significantly from their understanding by Russian law, which belongs to the Romano-German legal family. The right to choose the option of accepting the inheritance and the rules on the mandatory share, enshrined in Russian law, testify to the development of inheritance law towards a balance of interests of participants in inheritance relations by establishing new limits for implementation of the testator’s will.