An unprecedented coalition of 212 House and Senate Democrats have joined together in calling on the U.S. Supreme Court to strike down the anti-gay Defense of Marriage Act.

In a 35-page brief filed on Friday, congressional Democrats argue DOMA should be struck down because the law should be subject to heightened scrutiny and the law singles out gay and lesbian couples for harm. The case challenging the statute is Windsor v. United States.

“DOMA imposes a sweeping and unjustifiable federal disability on married same-sex couples,” the brief concludes. “It is ‘class legislation’ that lacks any rational connection to legitimate federal interests, thus violating the Fifth Amendment’s equal-protection guarantee.”

While House Democrats have filed friend-of-the-court briefs in cases challenging DOMA at lower appellate courts, the latest brief is unprecedented because for the first time Senate Democrats have signed on as well. The 172 House Democrats who signed the brief were joined by 40 Senate Democrats.

House Democrats who signed the brief include House Minority Leader Nancy Pelosi (D-Calif.) and Rep. Jerrold Nadler (D-N.Y.), who lead the effort to gather signatures, as well as the six openly LGB members of the U.S. House: Reps. Jared Polis (D-Colo.), David Cicilline (D-R.I.), Sean Patrick Maloney (D-N.Y.), Mark Pocan (D-Wis.), Kyrsten Sinema (D-Ariz.) and Mark Takano (D-Calif.).

Senators who joined in the effort are lesbian Sen. Tammy Baldwin (D-Wis.) as well as Senate Majority Leader Harry Reid (D-Nev.), Assistant Majority Leader Richard Durbin (D-Ill.) and Senate Judiciary Committee Chair Patrick Leahy (D-Vt.).

The brief devotes significant attention to disputing the arguments in favor of DOMA made by the House Republican-led Bipartisan Legal Advisory Group — which has taken up defense of DOMA in place of the administration — particularly BLAG’s argument that gays enjoy political power and thus aren’t a suspect class.

Congressional Democrats take note of how the LGBT people unable has been unable pass legislation to institute federal protections against job bias — the Employment Non-Discrimination Act — as an example of their political powerlessness.

“In fact, in the nearly twenty years since it was first introduced, ENDA passed only once in the House and never in the Senate,” the brief states. “That gay men and lesbians have been unable to achieve even the modest goal of obtaining basic protection against employment discrimination — despite the fact that 89 percent of the American people supports such protection — shows that BLAG is flat wrong in contending that gay men and lesbians enjoy ‘remarkable political clout.'”

The brief also details harm that DOMA causes same-sex couples who are unable to receive federal benefits of marriage — as well as the harm the statute causes children living in these families.

“Many married lesbians and gay men raise children together,” the brief states. “DOMA harms them and their children, and affords no benefit to different-sex couples or their children. It thus cannot survive equal protection review.”

Notably, the brief refrains from making the argument that Congress passed DOMA in 1996 out of animus — a position held by many LGBT advocates — and instead maintains it was made law because members of Congress at the time didn’t know gay people.

“From our perspective — including those of us who voted for DOMA — debate and passage of the law did not necessarily arise ‘from malice or hostile animus,’ but instead from ‘insensitivity caused by simple want of careful, rational reflection or from some instinctive mechanism to guard against people who appear to be different in some respects from ourselves,'” the brief states. “While fear and distrust of families different from our own may explain why DOMA passed by comfortable majorities in 1996, it does not obviate the need for a constitutionally permissible justification for the law.”

Evan Wolfson, president of Freedom to Marry, commended congressional Democrats speaking out against DOMA before the Supreme Court.

“It’s a key indicator of how indefensible the so-called Defense of Marriage Act is that now literally hundreds of members of Congress are signing a brief repudiating it,” Wolfson said. “These senators and representatives, like the American people they serve, know that the government shouldn’t be assigning second-class status to legally married same-sex couples.”

No Republicans signed the brief. Even though Reps. Ileana Ros-Lehtinen (R-Fla.) and Richard Hanna (R-N.Y.) have signed on as co-sponsors to legislation that would repeal DOMA — and penned their names to another brief from 131 Republicans arguing that California’s Proposition 8 is unconstitutional — their names are absent from the DOMA brief.

Ilan Kayatsky, a Nadler spokesperson, deferred comment on the absence of any Republican names from the DOMA brief to Republicans. Neither Ros-Lehtinen’s nor Hanna’s office immediately responded to a request to comment.

The argument presented in the brief is along the lines of the argument that the Obama administration made against DOMA in the brief the Justice Department filed last month.

On Thursday, the administration also filed a brief before the Supreme Court arguing Prop 8 is unconstitutional in addition to the DOMA brief. However, congressional Democrats didn’t do the same and only submitted on brief on DOMA.

Drew Hammill, a Pelosi spokesperson, said the Democratic leader was focused on building support for the DOMA brief and its argument that DOMA should be subject to heightened scrutiny will assist in efforts to overturn California’s marriage ban.

“The brief provides the congressional members’ perspective on why there is absolutely no legitimate federal interest in discrimination, and why, given the history of how DOMA was enacted, heightened judicial scrutiny is needed for federal laws that discriminate against the LGBT community,” Hammill said. “In making the case for heightened scrutiny, the amicus brief will assist the efforts to overturn Proposition 8.”

Hammill also said Pelosi has spoken out against Prop 8 and “appreciates” the Justice Department’s filing against the constitutional ban on same-sex marriage in California.

“From the outset, Leader Pelosi has strongly opposed Proposition 8, and believes that the legal advocacy by opponents of Proposition 8 has been outstanding,” Hammill said. “The Leader looks forward to the day when all Californians – and indeed, all Americans everywhere – have the right to marry who they love.  She appreciates the President’s strong leadership in favor of overturning Proposition 8 and of striking down DOMA.”

Asked in a follow-up email to clarify whether Pelosi believes Prop 8 is unconstitutional, Hammill replied, “She has said so repeatedly.”