The European Commission has issued a Green paper [1] that aims to make it easier for EU citizens to have their legal 
status in one country fully recognised in another.
For most of us, a major legal status is our marital status, which the EU calls our ‘civil status’ in order to take into account same-sex civil unions. But forcing one EU member-state to recognise the marriage laws of another member-state is a very obvious attack on the right of member-states to decide their own family law.
Family law is not a competence of the EU. But free movement of labour is. This paper proposes, in effect, to use the movement of labour competence to interfere in an area that is not a competence.
A green paper is only a discussion document and this one makes various proposals concerning harmonisation of legal documents some of which are less far-reaching than others.
Ultimately it will be up to the Council of Ministers which proposal, if any, it chooses to adopt. Hopefully it will throw out any proposal to harmonise our marriage laws.
However, if it chooses to harmonise marriage laws it opens up the distinct possibility that Irish same-sex couples will go to Spain, ‘marry’ under Spanish law, and then have their ‘marriage’ recognised under Irish law. That will make a mockery of our own law and will represent an incredible attack on Irish sovereignty.