The article on the legal aspects of the detention of a foreigner with mental disorder in a psychiatric hospital in the light of the law on mental health and the Civil Procedure Code describes the case in which a person without Polish citizenship and permanent residence in the territory of Poland is admitted to a psychiatric hospital without expressing consent to such an admission. The case described in the article is the more peculiar as until recently the binding law excluded the testing of legitimacy of admitting such a person to hospital and subjecting to treatment by the court supervising psychiatric hospitals, which could lead to patient abuse and offence, including even a charge of lawless imprisonment. The article refers also to the international law binding in Poland and the law of the European Union that could provide an appropriate connection between jurisdictions and eliminate the limitation in the competence of the Polish courts discussed above. Summing up the discussion, the author of the article points to the fact that the amendment of article 1110 of the Civil Procedure Code, permitting the verification of justification of detention of a foreigner in a psychiatric hospital resulted from the obligations that Poland assumed while ratifying international agreements which obliged it to non-discrimination of people with respect to their state affiliation.