This is a very good Wall Street Journal editorial about the federalism issues at state in the two gay marriage cases before the Supreme Court:
This week the Supreme Court takes up same-sex marriage, amid shifting American mores and a healthy debate about equality. Yet the two cases before the High Court are less about the institution of marriage than the sanctity of democratic institutions and the proper role of the courts.
Over time, through popular consent, the law comes to reflect an evolving social consensus. On gay marriage, state by state, election by election, voters are extending to gay and lesbian couples the same rights and responsibilities that pertain to a union between a man and a woman. Those choices are the pith of self-government, even if fair-minded voters in other states preserve the traditional meaning.
If the Supreme Court now reads a right to gay marriage into the Constitution and imposes that definition on all states, it won't settle the debates Americans are conducting. It will inflame them and ensure they never end, prematurely aborting the give-and-take on contentious moral and social issues the Constitution is designed to encourage. Five Justices—or fewer, if they split into pluralities—could further polarize the body politic and make compromise more difficult.
The editorial is at its weakest when it tries to argue that the federal Defense of Marriage Act is compatible with federalist principles. It says something like: When DOMA was passed, traditional marriage was the accepted norm in almost all states, and it is has been standard practice for 200 years for the federal government to borrow the states' definitions on a wide variety of things. When and if we evolve to the point where same-sex marriage is accepted as part of the norm, then it will be time to toss out DOMA.
I mean, I understand the logic of that position; I'm just not sure I buy it. I realize that federal law and state law are different things, and they don't always have to be identical, but it still seems inherently contradictory to me if the court says, on the one hand, this is something to be worked out state by state, but, on the other hand, it's OK for the federal government to issue a one-size-fits-all command. I don't see the court doing anything like this in any other context, saying, for example, it's perfectly OK for the federal government to outlaw marijuana as a dangerous drug while allowing states to approve it for medical or even recreational uses at the same time.