Recent developments apparently make it more likely that this matter will begin to move toward the Supreme Court, where the most important decision regarding the matter will probably eventually be made:
One of the most fascinating aspects of the recent court battles in California has been the involvement of Ted Olsen, a conservative, in support of gay marriage:
If the U. S. Supreme Court does rule that same-sex marriage is legal throughout the country, the debate will still probably continue and may even intensify, as has happened in the debate about the legality of abortion. Yet the Supreme Court ruling about abortion -- which would seem a much more potentially divisive issue -- remains law at this time.
This is already the legal case, in my opinion, it just has not yet been ruled on. Since marriage is a legal contract as well as a social one, gay marriage would also need to be recognized by states where it is not legal. In some states you can get married when you are 16 without parent permission. Even though it is not that way in my state, Washington still has to recognize those marriages as legal.
I, also, agree with posters #5 and #6. There are many laws that states chose to recognize or not. Same sex marriage, being a very controversial issue, would be one which states would fight. Given many states have not recognized same sex marriages as legal, it would not surprise me that some states would simply refuse to recognize same sex married couples--as they do not now.
Therefore, if they had to be recognized, states would simply have to decide if it were worth the fight in their own state to fight against it. In the end, it would seem that al states would simply be required to legalize same sex marriages. (Unfortunately, I find this would not happen that easily.)
#5 is correct. Right now the individual states make their own decisions about what is allowed within their borders (a position I agree with), but if there were a nationwide edict about the issue it would be something about which we would absolutely have to make a final decision. It would have to be binding, and everyone would have to abide by it, or it would become one of those laws that everyone knows but no one follows.
So the question isn't "should they be" it's "what if they were..." If they were, we would soon have a national law passed on the issue one way or another. The states that didn't want to have to honor same sex marriages would kick up enough of a fuss that they would force a decision one way or the other on the national level.
While I am not a constitutional lawyer, there is no doubt in my mind that the full faith and credit clause is applicable to the situation, and I wish I were arguing this case. If a custody order from Pennsylvania must be honored by a Florida court, and if a marriage certificate from California must be honored by a court in Virginia, it is completely unclear to me why the same would not apply to same-sex marriage. In each situation, one state might very well have different laws or different requirements from another. Yet we think nothing of insisting on full faith and credit in these instances. It is ironic that most people who oppose same-sex marriage, which I, too, support, are people who are always advocates of states' rights. Yet in this instance, those very same people would like a federal constitutional amendment that would take away states' rights and have the temerity to think that the rights of states that allow same-sex marriage do not exist.
Some have argued that the Constitution's "full faith and credit" clause, or even the 14th Amendment, requires exactly this. This is what the so-called "Defense of Marriage Act" was intended to legislate its way around. The Act has been ruled constitutional on these and other grounds by state courts around the country, and the Obama Administration has said that parts of DOMA are unconstitutional. But these court decisions are under appeal. Removing personal opinion from the issue (I support same-sex marriage, in the interest of full disclosure) it will be interesting to see from a legal standpoint how these issues play out.