Ari Ezra Waldman explains why SCOTUS spent so much time on it today:
The DOMA case raises its own standing concerns that could get it thrown out, which is why the Court allocated a full 50 minutes just to the standing question. Setting aside so much time to one specific question, however, does not necessarily mean the justices are more focused on standing in DOMA than they were in Prop 8. Rather, because all parties have always agreed that standing was met, the standing question was never fully addressed. Think of the first 50 minutes as the Court’s attempt to make sure it gets all sides of the issue, with Harvard Law Professor Vicki Jackson arguing against standing. Then, the Court moved to the merits, which is where it got interesting.