Same-sex relationships have successively qualified for formalization through marriage or registered partnership in many European countries. However, some EU Member States still refuse to give them any form of recognition or only allow very limited legal effects. The irregular speed of development in domestic family laws in EU Member States results in 'limping family' relations, that is, family relations that are recognised as creating a formal civil status in many EU Member States, but not in all of them. The ordre public safeguard of private international law has widely been used to justify why a same-sex marriage or registered partnership cannot be recognised. The pretext tends to be that national identity, allegedly, becomes threatened. Nevertheless, the case-law of the European Court of Human Rights and the Court of Justice of European Union provides new standards for recognition, which create legal obligations for EU Member States.