The starting point is that there is no legal certainty without substantive res judicata. The extent of substantive res judicata is determined by the parties' claims because of the alleged legal limitation.   At the same time, this determines both the action and its subject-matter. Hungarian civil procedure law represents a strict approach to the material scope of substantive res judicata and interprets its concept narrowly.   However, German civil litigation law, which serves as a model for Hungarian litigation law, partly takes a different view, precisely because it denies that the claimed law is attached. At the same time, during my research, it became clear that the perception of substantive res judicata and thus of the alleged right also influences the parties' access to law. I shall therefore analyse these issues, which are partly constitutional.

Determining the content of foreign law is a complex issue. It relates to the requirement that litigation be adjudicated within a reasonable time, the area in which litigation costs are to be paid and the alleged legal limitation.   My starting point is, on the one hand, that the determination of the content of foreign law is not proof - this also determines the question of the bearing of litigation costs - and, on the other hand, that foreign law determines the law asserted in the lawsuit. That is, the court is bound by this right in its decision-making.   At the same time, determining the content of a foreign law may take several years, so the court must always assess whether it is more expedient to act on the basis of Hungarian law. However, this also raises the problem of the parties' right of disposal and the alleged right of conservation.

Within this field of research, I examine issues related to family law and court proceedings. Thus, I focus on listening to children, including what judgment means in the case of a child.   Family law litigation also requires special rules for filing proceedings, precisely because of the presence of the child, and I will analyse this as well, i.e. whether the special litigation prescribed by law is suitable for taking into account the interests of the child.   The above two aspects are closely related to the issue of ex officio evidence, as the Hungarian Code of Procedure provides for this possibility only in these cases. It is questionable whether the regulation is appropriate and whether it is really in the interests of the child. In my research, I will also review these questions.