On Monday, House Republicans are scheduled to weigh in with a federal court in New York on the side of a law called the Defense of Marriage Act.
Big majorities in Congress passed the law 15 years ago to define marriage as being between a man and a woman. Usually, it's the Justice Department that speaks up when federal laws are challenged in court. But in this case, the Obama administration has declined to defend a law it considers unconstitutional.
The decision generated controversy among conservatives and even within the Justice Department.