The Defense of Marriage Act (H.R. 3396), or DOMA for short, was a law written up by Congressman Bob Barr (R-GA) that was passed overwhelmingly by Congress back in 1996. The bill stated that no state needs to treat a same sex marriage as a marriage, and that the federal government defines marriage exclusively as a union between one man and one woman. This piece of federal legislation has defined the legal definition of marriage in our modern time. However, a federal judge, Joseph Tauro, in Massachusetts has undone that by ruling that the legislation is a violation of the Tenth Amendment.
For the sake of the Constitution of the United States of America, this judge deserves kudos for standing up for the Tenth Amendment.....you know, the amendment that states that anything not explicitly delegated to the federal government goes to the States or the people. Many of those on the Religious Right just love using the Tenth Amendment to argue against Roe v. Wade, which they rightfully should. But when that argument comes right back at them with regards to same-sex unions, they go ballistic.
I think what many people [like to] forget is that the purpose of the judicial system is judicial review, a practice in this country that is extracted from Article III of the Constitution and dates back all the way to Marbury v. Madison. Judicial review, which is not to be confused with judicial activism, is one of the primary balances that the judicial branch has on the legislative branch. It gives the courts the power to rule whether an enacted law is constitutional or not.
That is what Tauro did--he did his job by ruling that DOMA is unconstitutional. Whether it was Tauro's intention to bring balance of power between the state and federal government is moot at this point. This case brings the Tenth Amendment back to the arena, thereby discontinuing the centralization of power at the federal level. The judge also ruled that it violates the Due Process clause of the Fifth Amendment, which essentially is the equivalent of an equal protection clause, which is an interesting argument that is expounded upon here, along with more descriptive about how it violates the Tenth Amendment.
Regardless of your opinion on the matter, I think one thing that everybody can agree on is that the resultant of this federal court decision is going to play a huge role in how laws regarding the definition of marriage will play out in future legislation.