Article 2 of the U.S. Constitution requires that each new president take the following oath:

“I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my ability, preserve, protect and defend the Constitution of the United States.”

President Obama announced this week that he will violate that oath.

In a decision hailed by gay-rights activists, the White House announced that it will no longer defend the Defense of Marriage Act (DOMA) on the grounds that it has suddenly dawned on the president and attorney general that the law is unconstitutional.

DOMA, signed into law by President Clinton, bars the federal government from recognizing same-sex marriages. Obama has always opposed the law, but as president his administration has enforced it and defended it in court. Although it should be noted that Obama’s Justice Department has not defended DOMA vigorously, as Justice Department guidelines require.

As Ed Whelan, a legal scholar and president of the Ethics and Public Policy Center, has detailed at some length, the DOJ has been, in effect, tanking the fight in court for the last two years by tailoring its arguments in ways beneficial to gay-marriage activists. Now Obama’s lawyers are simply taking a dive by flatly declaring the unconstitutionality of the law.

Obama, who fancies himself a scholar of the Constitution, never said a peep about the law being unconstitutional until this week.

Why the public change of heart?

There’s good reason to believe that Obama has always been lying – yes, lying – about opposing gay marriage. For example, in 1996, he told The Windy City Times, “I favor legalizing same-sex marriages, and would fight efforts to prohibit such marriages.” But by 2004, Obama very much wanted to be president, and he understood that supporting gay marriage would be a political liability. So he opted for something other than honesty. And in a 2004 interview with a gay publication, Obama strongly hinted his opposition was strategic, not philosophical.

“Everything we know and admire about President Obama makes the claim that he doesn’t support the freedom to marry very unconvincing,” Evan Wolfson, the director of the gay-rights group Freedom to Marry, told the Huffington Post last August.

White House Press Secretary Jay Carney insists that the president still opposes same-sex marriage. But Carney was quick to note that the president has said his views on the matter are “evolving.” Translation: He could completely change his mind at any moment.

And you know what? That’s fine. Lots of people change their minds about issues like these. Support for gay marriage and gay rights generally has been on the rise for years. My own views have been evolving as well.

But that is all irrelevant. The politics are irrelevant too. I don’t know if this is a politically smart move on Obama’s part or a dumb one, though I have my theories.

Either way, what Obama is doing is flatly outrageous. Carney says that “the president is constitutionally bound to enforce the laws and enforcement of the DOMA will continue.”

No, he is not.

There’s a myth out there that only the Supreme Court determines what is, or is not, constitutional. It’s a bipartisan myth. “We can’t have presidents deciding what laws are constitutional and what laws are not,” Republican Sen. Scott Brown of Massachusetts said in a statement. “That is a function of the judicial branch, not the executive.”

President Bush made a similar, indefensible error when he signed the McCain-Feingold campaign finance bill, even though he believed portions of it were unconstitutional (and he was right; the Supreme Court overturned it in Citizens United v. Federal Election Commission last year).

The problem is that the Constitution doesn’t say any such thing (and, no, it’s not in Marbury v. Madison either). The president doesn’t take an oath to “preserve, protect and defend” the Supreme Court. He takes an oath to defend the Constitution.

Imagine if Congress passed – hopefully over a presidential veto – a law that brought back slavery. Such a law would be plainly unconstitutional, and no president worthy of the job would wait for the Supreme Court to tell him as much. More to the point, once the president concluded that the law was unconstitutional, he would be bound by his oath to ignore it, and challenge it in every way possible.

President Obama says DOMA is unconstitutional, and yet the “law professor” says he will continue to enforce it.

In a properly ordered constitutional republic, this would be a scandal. But in America today, it’s cause for eye-rolling, shrugs and platitudes about the demands of politics.

© 2011 Tribune Media Services, Inc.