The article deals with the procedural problems of considering civil cases on the invalidation of a will made by a person who is not able at that moment to understand the meaning of his actions or to manage them. The peculiarities of this category of cases are the epistemological limited possibilities for proving and the short period of effective protection of rights in court - up to six months, as well as the difficulties associated with establishing the personality of the proper defendant. Material and procedural ways of solving the problems described in the article are proposed. In particular, it is proposed to provide heirs who would be called to inherit in the absence of a will, the right to receive information about contents from persons who certified the will, , the right to challenge wills before opening the inheritance in accordance with the rules of paragraph 2 of Art. 177 of the Civil Code of the Russian Federation or the opportunity to file a corresponding claim in court without specifying the defendant. It is proposed to fix formally in the acts of the Plenum of the Supreme Court the need to raise the issue of appointing a post-mortem forensic examination in any case of the category under study. It is also proposed to narrow the breadth of discretionary powers of the court when resolving a petition for a repeated forensic examination in the category of cases under study.