Yesterday, Proposition 8 was overturned by Judge Vaughn Walker of the United States District Court for the Northern District of California. While this isn't insignificant, it is certainly not going to be the final step in this process. It is the first ruling in what will likely be at least three decisions on this issue.
The decision will be appealed to the 9th Circuit Court of Appeals. It is probably the most Liberal of the Circuit Courts and will likely agree with the ruling of the lower court. There is always the potential that the case could be sent back to the lower court if the Court of Appeals feels something is unclear or some other issue arises. It doesn't really matter what this court's decision is, because the next step will be an Appeal to the United States Supreme Court.
Under the assumption that Elena Kagan will turn out to be a liberal Justice, the Supreme Court will be a 5-4 decision on the issue. There are four Liberal Justices, Sotomayor, Breyer, Kagan, and Ginsberg, who will likely support the overturn of Prop 8 and have sympathetic view of an Equal Protection Case. There are four justices that are conservatives, Alito, Scalia, Roberts, and Thomas, who will likely support overturning the rulings of the lower courts.
The swing vote will be Justice Anthony Kennedy. He has shown some support of Homosexual rights in siding with the majority and writing the opinion in the case of Lawerence v. Texas, which ruled a sodomy ban unconstitutional, and sided with the Majority in Romer v. Evans, ruling that preventing discrimination claims by homosexuals in Colorado was unconstitutional. He's not entirely gay-friendly though as he has voted to uphold bans of homosexuals by private organization such as the Boy Scouts. It is generally hard for me to trust a Justice who was in the Majority of Bush v. Gore, but I think Kennedy would likely side with the Liberals to overturn Prop 8. That would set new precedent that would lead to all state bans on gay marriage being overturned.
Another important step would be the repeal of the Defensive of Marriage Act. This act is ridiculously unconstitutional. Basically this act makes it so states do not have to recognize the gay marriages performed in other states. So, a couple could get married in a state like Iowa, but as soon as they cross the state line they would no longer be legally married. This is an absolute violation of the Full Faith and Credit clause and the principles of federalism. I really don't understand how this law hasn't been overturned yet, but I know the people who passed it in 1996 knew it would overturned. I think it was just something that legislators at the time wanted to pass, so they could score political points by going back to their districts and braging about sticking it to the fagots and then bitch about the judges when it was over turned.
Back on the point. If the ban in California is overturned by the United State's Supreme Court, but DOMA still stands, it would create a country where each state had to allow gay marriage in their own states, but didn't have to recognize any gay marriages performed outside of their own state.