House Democrats today filed a brief in support of a legal challenge to the Defense of Marriage Act, the 1996 law that defines marriage as between one man and one woman.

The amicus brief filed by 133 Democrats, including the party’s top leaders, maintains that Congress hastily passed legislation during President Bill Clinton’s presidency to limit who can marry and asserts that the law is unconstitutional. The brief was filed in a consolidated court case being considered in the 1st U.S. Circuit Court of Appeals, although a release said House Minority Leader Nancy Pelosi (Calif.) and other top Democratic leaders who oppose the law will file similar briefs in other pending court cases.

“Congress passed DOMA without examining its impact on any of the thousand-plus federal laws that take marital status into account or hearing from child welfare or family law experts,” the brief states. “Nor did Congress pause to examine why the federal government traditionally has respected state marriages for purposes of federal law despite the non-trivial differences in state marriage laws over this Nation’s history before rupturing this longstanding federalist practice.”

Separately, a large collection of businesses, cities and professional organizations, including Microsoft, Google and Aetna, filed a brief against the law, according to a release.

Democrats cheered President Barack Obama’s declaration in February that DOMA was unconstitutional and his instructions to the Justice Department not to defend it in court. The move sparked a flash point in the culture wars and prompted Speaker John Boehner (R-Ohio), following a party-line vote by the Bipartisan Legal Advisory Group, to hire outside lawyers to defend the law in pending court cases. While Boehner has taken steps to ensure the law is upheld, Congressional Democrats have pushed to overturn it.

The amicus brief is the latest in the Democrats’ lobbying effort. It asserts that DOMA impedes on state marriage laws and maintains that support in the House for the law is eroding. Thirteen of the letter’s Democratic supporters voted for the DOMA bill in 1996. Still, legislation to overturn the law has no chance of passing in the House or the Senate. The Senate Judiciary Committee is slated to vote on a repeal bill next week, and while it is expected to win approval in the committee, it does not have the 60 votes needed to break a potential filibuster and move to the floor.