Elf Sternberg

That's an open question. The legislative discussions surrounding DOMA say that Congress replied on the second sentence of the Full Faith and Credit clause to justify the legality of the law.

But it's very iffy. The clause reads "And Congress may prescribe the manner in which such acts, records, and proceedings shall be proved, and the effect thereof." (emphasis added). The intent of the whole full-faith-and-credit clause was to force states into recognising each others records. Congress can force reluctant states into doing so by saying that if the proof of the record is in a particular form, then the reluctant state must accept it.

Example: In 1948, the California Supreme Court ruled that blacks could marry whites. Other states disagreed, and could very well have chosen to ignore California marriages which did not follow that state's laws. The Full Faith and Credit clause says they had to, but the state could very well set enormously high standards of proof of such a mixed-race marriage. Congress could step in, and say that a marriage certificate, sealed by the appropriate state agency of the state in which the marriage was licensed, constitutes proof. Then a state which does not allow miscegenation would be forced to recognise a mixed-race marriage legally performed in California.

It is hard for me to agree that a law that says that certain records from another state can be ignored depending not on the manner the evidence is presented but rather on the participants in the record could be considered constitutional.

But until one state issues a marriage certificate to a same-sex couple, and that couple tries to legally claim benefits of marriage in another state that has chosen to ignore same-sex marriages from other states, and the couple takes the issue to court, the law will stand unchallenged.