Each of the 10 senators now asking the Supreme Court to uphold the Defense of Marriage Act, known as DOMA, voted for it in 1996 either as senators or as House members.
In a friend-of-the-court brief filed Jan. 29, the senators said it is inconsistent for the Justice Department to have assured Congress the law was constitutional while it was being crafted in the mid-1990s but to raise questions now.
"The time to speak was in 1996, when Congress gave careful consideration to the need for DOMA," said the senators, all of whom are Republican.
But the senators acknowledged that public sentiment toward same-sex marriage has changed in the subsequent 17 years: "It is manifest that the traditional definition of marriage, which was overwhelmingly supported by bipartisan majorities in 1996, is more controversial today, both among the public and their elected representatives."
The law did not prohibit states from recognizing same-sex marriages, and nine states have enacted laws doing so since 1996. But the law also doesn't require states to recognize those marriages from other states, which makes many couples ineligible for federal spousal benefits under Medicare, Social Security and other programs if they change residences.
Two different federal appellate courts last year upheld several lower courts' rulings that DOMA is unconstitutional. The Supreme Court took up the case in December and has set oral arguments for March 27.
Obama two years ago instructed U.S. Attorney General Eric Holder to stop defending the law in federal court, an unusual move that places U.S. Solicitor General Donald Verrilli Jr. in a difficult spot, because the solicitor general normally defends federal laws under challenge before the high court.
House Speaker John Boehner, on behalf of House Republicans, has hired prominent Washington lawyer Paul Clement to defend the law, in a move that House Democratic leader Nancy Pelosi criticized for costing taxpayers $3 million.
In a related development, outgoing Defense Secretary Leon Panetta on Monday extended some minor benefits to the same-sex spouses of service members, making available perks that the Pentagon previously had denied.
In explaining why he hadn't extended all military benefits to same-sex spouses of service members, Panetta made an indirect reference to the high court's pending review of the 1996 Defense of Marriage Act.
"I foresee a time when the law will allow the [Defense] Department to grant full benefits to service members and their dependents, irrespective of sexual orientation," Panetta said. "Until then, the department will continue to comply with current law while doing all we can to take care of all soldiers, sailors, airmen, Marines and their families."
The benefits Panetta extended are relatively minor, among them access to hospital child care services, hospital visits and military ID cards that will enable the same-sex spouses to visit grocery stores, movie theaters, gyms and other outlets on bases. More major benefits such as medical care, housing allowances and survivor allowances are still withheld.
Panetta said his extension of limited benefits resulted from a review prompted by the September 2011 repeal of the Pentagon's "don't ask, don't tell" policy prohibiting gays from serving openly in the military.
The 10 senators
Senate Minority Leader Mitch McConnell, Ky.
Sen. Lindsey Graham, S.C.
Sen. Mike Crapo, Idaho
Sen. Saxby Chambliss, Ga.
Sen. Thad Cochran, Miss.
Sen. Roger Wicker, Miss.
Sen. Orrin Hatch, Utah
Sen. Dan Coats, Ind.
Sen. Charles Grassley, Iowa
Sen. Richard Shelby, Ala.