“We have only begun to fight,” said Brian Brown, president of the organization. He also said that with Holder’s announcement, Obama “unilaterally” declared homosexuals “a protected class” under the Constitution and would effectively make a federal court decision on the law “unreviewable by higher courts.”

While Obama favors repealing the law, Holder said the president has supported defending it as constitutional if a state or local law meets the legal standard of having “a rational basis” for singling out people for different treatment based on sexual orientation.

But in the pending cases, Holder said, the administration “faces for the first time the question of whether laws regarding sexual orientation are subject to the more permissive standard of review or whether a more rigorous standard, under which laws targeting minority groups with a history of discrimination are viewed with suspicion by the courts, should apply.”

Obama “has concluded that given a number of factors, including a documented history of discrimination, classifications based on sexual orientation should be subject to a more heightened standard of scrutiny,” Holder’s statement said.

He added that Obama has concluded that the law “as applied to legally married same-sex couples, fails to meet that standard and is therefore unconstitutional. Given that conclusion, the president has instructed the department not to defend the statute in such cases. I fully concur with the president’s determination.”

The U.S. bishops’ Office of General Counsel said refusal to support the law was “a grave affront to the millions of Americans who both reject unjust discrimination and affirm the unique and inestimable value of marriage as between one man and one woman.”

It also stressed that support for traditional marriage “is not bigotry,” but is a “reasonable, common judgment affirming the foundational institution of civil society.” The office said that “any suggestion by the government that such a judgment represents discrimination is a serious threat to the religious liberty of marriage supporters nationwide.”

Holder said the legal landscape has changed since the law was passed, including with Supreme Court rulings overturning laws criminalizing homosexual conduct and the repeal by Congress of the military’s “don’t ask, don’t tell” policy.

Unless Congress repeals the Defense of Marriage Act, or a final court ruling strikes it down, it will continue to remain in effect and the administration will continue to enforce it, Holder noted.

“But while both the wisdom and the legality of (the pertinent section of the law) will continue to be the subject of both extensive litigation and public debate, this administration will no longer assert its constitutionality in court,” Holder said.

Bill Donohue, president of the Catholic League for Religious and Civil Rights, said the decision by the Obama administration reflects the president’s views 15 years ago when he was running for the Illinois state Senate. At the time, he said he favored legalizing same-sex marriage and would fight efforts to prohibit such marriages.

Donohue said Obama endorsed civil unions in 2004, but that during his presidential campaign he spoke of marriage as a union between a man and a woman.

“Now Obama is officially on record as president opposing the defense of marriage,” said Donohue’s Feb. 23 statement. He said the president was not only going against the 1996 law but also was “in opposition to the over 30 state initiatives affirming marriage as a union between a man and a woman.”