The aim of the comparative analysis presented here was in a way to show a catalogue of ways of handling cases in which the complainant is incarcerated. Additionally the aim of this study is an attempt at explicating the current legal status in Poland in terms of the institution of lodging complaints by detainees and its functioning, and to compile a comparative analysis in the same subject area. In addition, the aim of the study is an attempt to present de lege lata conclusions and de lege ferenda postulates in the context of the matter in question. It should be emphasized that the institution of a complaint is notoriously used by persons deprived of their liberty, which is clearly visible in the statistical analysis presented in the article. For this reason, it seems justified to undertake legislative work in cooperation with the Ministry of Justice and the Central Management of the Academy of Justice. This study uses a triangulation of the following research methods: descriptive research method, theoretical and legal method, comparative method with the elements of comparative law, and statistical method. The legal status adopted in the paper as on 30 October 2020.