...here's why he would have voted for it if he had been in Congress in 1996:
"While marriage is licensed and otherwise regulated by the states, government did not create the institution of marriage. In fact, the institution of marriage most likely pre-dates the institution of government! Government regulation of marriage is based on state recognition of the practices and customs formulated by private individuals interacting in civil society. Many people associate their wedding day with completing the rituals and other requirements of their faith, thus being joined in the eyes of their church and their creator, not with receiving their marriage license, thus being joined in the eyes of the state.
If I were in Congress in 1996, I would have voted for the Defense of Marriage Act, which used Congress's constitutional authority to define what official state documents other states have to recognize under the Full Faith and Credit Clause, to ensure that no state would be forced to recognize a “same sex” marriage license issued in another state."
(I'm only posting this because I've heard a few people in the MSM claim that he actually voted for it. What Paul did sign was the 2007 Marriage Protection Act.)
UPDATE: Michael Johnson notes:
Full Faith and Credit shall be given in each State to the public Acts, Records, and judicial Proceedings of every other State. And the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof.
Where is this Authority Congress possesses to EXCEPT public Acts, Records and judicial Proceedings from being given Full Faith and Credit?
A cursory bit of research reveals the phrase "and the effect thereof" does not provide for exceptions to public acts, records and judicial proceedings being given Full Faith and Credit by all States, but serves to provide that these records be given the same footing in other jurisdictions as the original. For instance, it gives them the same faith and credit, as they have in the State court, from which they are taken. If in such court they have the faith and credit of the highest nature, that is to say, of record evidence, they must have the same faith and credit in every other court. So, that Congress have declared the effect of the records, by declaring, what degree of faith and credit shall be given to them. If a judgment is conclusive in the State, where it is pronounced, it is equally conclusive every where. If re-examinable there, it is open to the same inquiries in every other state.