Combined, they could soon require each of the EU's 28 member nations to extend the rights and benefits of marriage equality to LGBTQ people across Europe - European Union gay marriage right would be gigantic deal affecting untold hundreds of thousands of people.
Advising the European Court of Justice on the case, Advocate General Melchior Wathelet said Thursday balanced Romania's interest in protecting "the traditional family" against its obligation not to discriminate on grounds of sexual orientation.
Advocates general's opinions are not binding, but the court often rules the same way as the advocate general.
The case involves a Romanian male national who had married a man from the United States in Brussels in 2010.
"Granting the spouse of a union citizen a right of residence constitutes recognition and the minimum guarantee that can be given them", the opinion concludes.
In his Opinion delivered today, Advocate General Wathelet states, first of all, that the legal issue at the centre of the dispute is not that of the legalisation of same-sex marriage, but that of the free movement of European Union citizens.
In those circumstances, the Advocate General is of the opinion that the concept of "spouse" within the meaning of the directive also includes spouses of the same sex.
But, the impact of the decision will change the right to same-sex spouses in the countries who don't already give same-sex couples this right. The couple met in NY in 2002 and lived together there for four years, but Hamilton remained in NY initially when Coman moved to Belgium for work.
Adrian Coman and Clai Hamilton are the couple at the center of this groundbreaking case.
Hamilton hopes the ruling will be positive for LGBTI Romanians too. Romania, which does not allow same-sex marriages, refused.
In 2013, after Romanian immigration officials denied their application, they filed suit in Bucharest.
In 2012, they asked for residency permits for Mr Hamilton to live and work permanently in Romania but were turned down.
"The fact that Mr. Hamilton did not live continuously with Mr. Coman in [Brussels] does not seem to me to be capable of rendering their relationship ineffective", he wrote. We can hopefully now be closer to being recognised as a family. And that's only on the basis of his American passport.