Marriage and family are protected at the constitutional level. In order to secure the subjective shape of marriage the legislator in Poland, in the Constitution of 1997, defined marriage as a union of a man and a woman (Article 18). However, this regulation, especially its formulation, is a source of doubts concerning the possibility of institutionalisation of same-sex marriages (and possibly other unions). The question arises whether it is possible to regulate the ordinary law allowing for marriage (and possibly other unions) of same sex couples or the constitutional norm excludes such a possibility. There are also further questions about the possibility of any other form of institutionalization of same-sex unions. For this reason, the aim of this article is to show the impact of constitutional provisions on the possibility of regulating marriage or other same-sex unions by law. Against this background, the paper considers whether there exists in Poland a constitutional ban on marriage or other same-sex unions which would prevent their statutory institutionalization. The influence of international regulations on the issue of such regulations, including the
European Convention on Human Rights and the International Covenant on Civil and Political Rights, as well as EU regulations contained in the Charter of Funda- mental Rights, is presented. The Spanish legislation serves as a point of reference
and a possible model to follow in the context of resolving this type of legislative dilemma for the Polish legislator, where with constitutional solutions relatively similar to those in Poland, homosexual marriages and partnerships have been institutionalised for a long time.