Last week, David Boies — the liberal half of the super-legal team that filed a federal challenge to Prop 8 — wrote a lengthy piece in the Wall Street Journal explaining why he was fighting for marriage equality.
Over the weekend, his Conservative partner-in-equality Ted Olson gave an interview to the LA Times explaining why he is fighting for marriage equality:

I wanted to convey the message that this was not Republican or Democrat, conservative or liberal, that this is about human rights and human decency and constitutional law. David was my opponent in Bush v. Gore, but he’s someone for whom I have great respect and affection. We spend some time together once in a while socially. We’ve done some biking in Europe together. He didn’t hesitate for a second.
. . . It is a conservative value to respect the relationship that people seek to have with one another, a stable, committed relationship that provides a backbone for our community, for our economy. I think conservatives should value that.
This is pretty much the same argument that Andrew Sullivan and others have been making for years. And it’s a good one.