Gingrich is standing on solid ground with his reasoning.
Actually he's not. Perhaps instead of being a history major he should have gone to law school. Twice the Reagan administration refused to defend laws it felt were unconstitutional (1982 IRS versus Bob Jones University, and in 1983 where the DOJ joined with the plaintiff petitioning the Court of Appeals for review of a deportation order that the plaintiff believed to be unconstitutional). Bush I did it in Metro Broadcasting v. FCC and Bush II did it with ACLU v Mineta. In the ACLU case, just the same as Holder has done here with the DOMA, the Solicitor General explained the administration’s decision in a letter to Congress where he wrote,
“the government does not have a viable argument to advance in the statute’s defense and will not appeal the district court’s decision.”
All in all, thirteen times the president's administration has refused to enforce laws it felt were unconstitutional, and in many of those cases the laws were on the books for a while.
Under federal law, the President is required to inform Congress when the DOJ chooses not to support the constitutionality of a particular act of Congress. The legal justification for these actions has long been accepted law and goes to the very oath of office that Newt seems to feel the president is violating in his DOMA decision.
One of the greatest threats to the Constitution is the enactment and enforcement of unconstitutional laws that exceed the powers of government. The president takes an oath to “preserve, protect, and defend” the Constitution.
His duty to uphold the Constitution supersedes his obligation to enforce federal statutes when the two come into conflict. After all, federal statutes are only legitimate in so far as they are constitutional.
George Washington was the first to do it, and presidents ever since have exercised their own judgment in assessing the constitutionality of federal laws, and have not simply deferred to the courts or to Congress. Each branch of government has an independent responsibility to assess the constitutionality of current and proposed laws. This is not incompatible with the duty of the president or Congress to obey judicial decisions that strike down a statute, since the Constitution gives the courts jurisdiction over all cases arising under it. But if the courts haven’t yet ruled on the issue, nothing prevents the president or Congress from making a considered independent judgment that the statute is nonetheless unconstitutional and acting accordingly.
As Justice Scalia noted in Freytag v Commissioner, 501 US 868, 1991,
Thus, it was not enough simply to repose the power to execute the laws (or to appoint) in the President; it was also necessary to provide him with the means to resist legislative encroachment upon that power. The means selected were various, including a separate political constituency, to which he alone was responsible, and the power to veto encroaching laws, see Art. I, 7, or even to disregard them when they are unconstitutional.
I don't know which is worse, Gingrich running around spouting lies, or a citizenry so uninformed that they lap it up as gospel. The constitutionality of a law doesn't depend on whether you are agree with it, it depends on whether or not it's constitutional. If any branch of government feels a particular law or an application of the law is unconstitutional, they have an obligation under the constitution to not enforce it.
It should also be noted that, according to the letter from Holder, the President's administration is only declining to defend the constitutionality of Section 3 which deals with forbidding federal government recognition of same sex marriages contracted in the states, while continuing to argue the provisions in DOMA that allow states to refuse to recognize same-sex marriages contracted elsewhere.
And, just because the President or his AG refuses to enforce a law doesn't mean the law won't have able defenders elsewhere. In the Bob Jones case mentioned above where the Reagan administration refused to defend an IRS policy denying tax exemptions to a university that practiced racial segregation for religious reasons, the IRS policies, and not the Bob Jones University policies, were ultimately upheld by the Supreme Court, as other able lawyers were found to defend them. The same thing may very well end up happening with the DOMA, as there are states with certain tax benefits from federally recognized marriages, and some of all of these states could very well defend the Act.
So no, Gingrich isn't on solid ground with his reasoning at all. He's just flat out wrong. If he's going to try to make the point that America is a nation ruled by law, then he should probably know what those laws are which pertain to the President and Congress, especially since, you know, he used to be a legislator and is considering running for President.