As oral arguments were beginning Tuesday in the first of two same-sex marriage cases inside the Supreme Court, the steps in front of the court were filled with throngs of what looked to be mostly gay-marriage supporters, spilling out in front of the building and to the other side of the street.
About a half hour earlier, a parade of traditional-marriage supporters had arrived, later headed to a rally on the National Mall.
When advocates for gay marriage talk about it, they usually focus on the struggle for equality and civil rights.
But how the Supreme Court decides the Defense of Marriage Act case being argued this week could possibly have big implications in another arena — the money same-sex couples owe the Internal Revenue Service.
The case that could throw out a law that defines marriage as between a man and woman started with a tax bill.