The basic question that it will come down to is state's rights vs federal rights.
Remember that the US is a republic - it is a nation formed of individual states.
In the past marriage has always been a state issue, and the states have had to work out their own definitions and agreements.
If any of this makes it to the supreme court the question will hardly be, "Is gay marriage ok" it will instead be, "Do states have the autonomy to continue to define marriage."
It is unlikely that the states will cede even more power to the federal government, even if someone, somehow can prove conclusively to the 9 that the US constitution guarantees this as a "right", which certainly isn't nearly as cut and dried a case as many here seem to think.
The funny thing, though, is that the California issue is a microcosm of the US - it's a catch-22 for gay rights supporters. Right now no one is seriously considering an amendment to the US constitution to ban gay marriage because that decision belongs to the states.
If the supreme court rules that the federal government is now in charge of the definition of marriage, and takes that right from the state, then the opposition has a much simpler job:
Rather than amending each state constitution to ban gay marriage, they can do it once for the US constitution.
California is much more socially liberal than the rest of the US. It'll be so much easier to amend the US constitution with a gay marriage ban than it was to amend the california constitution.
Rather than taking it to the courts, the activists should have simply rallied the public behind them, and struck the amendment out. I really think they're shooting themselves in the foot by taking to the courts rather than the voters.
