Several European countries have taken the step of allowing same-sex couples to legally formalize their relationship, through the institution of registered partnership or through a gender-neutral marriage institution. The Nordic countries are in the lead. In this way, the legal systems want to distance themselves from unequal treatment based on sexual orientation or gender. This process has been facilitated by a dynamic interpretation of rights guaranteed by the European Convention on Human Rights (ECHR) and the EU Charter of Fundamental Rights, although these in themselves do not oblige states to 'marry' same-sex couples. At the same time, this development has met with strong resistance in the Baltic region, not least in Poland, Latvia and Lithuania, which reject homosexuality and emphasize traditional family roles. The lack of a unified European 'approach' leads to legally 'limping' family relationships; a relationship is recognized in one country but not in another. This PhD project analyzes the ideas of free movement and equal rights of citizens and the right of each Member State to maintain its national specificity, in the context of same-sex relationships. The analysis takes into account, on the one hand, the new EU international family law regulations, primary EU law and the ECHR, and on the other hand, the legal situation primarily in the Baltic EU states of Lithuania, Latvia and Poland. The central research question is to examine the potential of the Europeanization process to bring the countries' legal systems closer together.