Here's the problem with DOMA, and I think George Will raised it:
What if DOMA was passed in the 1970s in response to the introduction of no-fault divorce? What if the Federal Government for the purposes of FEDERAL law defined marriage as 1 man, 1 woman FOR LIFE unless dissolved by a court on very specific FAULT grounds?
What then? How would you deal with a man who no-fault divorced his first wife against her will in Nevada in 3 days, and then remarried another woman 6 months later in the same tax year? The Federal government is not bound to accept the judgements rendered by lower courts, so if a Judge entered a no-fault decree, hypothetically the Feds would not have to honor it.
And Marriage has already been redefined with no-fault