Bill Duncan of the Marriage Law Foundation writes:

When Eric Holder wrote to Speaker Boehner to inform him of President Obama's decision that DOMA was unconstitutional, he said it was unconstitutional under the "equal protection" provisions of the Fifth Amendment.

Huh?  Why the Fifth Amendment, which does not mention equal protection at all--but does contain a "due process" clause?

There is a reason.

When the Supreme Court decided racial segregation in schools violates our Constitution in Brown v. Board of Education, the 14th Amendment applied to the states, but not to federal territory. That would leave D.C. schools segregated, since the District is federal territory.  So the Court did a backflip in a companion case called Bolling v. Sharpe that held the 14th amendment's equal protection guarantees were now incorporated into the Fifth Amendment's due process guarantees.

On race, we can understand why a Court would do a backflip. But this underscores how much President Obama has just attempted to re-classify sexual orientation as the constitutional equivalent of race--without any backing by Congress or by the Court.