The filing Friday in San Francisco's U.S. District Court comes in a lesbian federal employee's lawsuit that claims the government wrongly denied health insurance coverage to her same-sex spouse. Karen Golinski says the law under which her spouse was denied benefits -- the Defense of Marriage Act -- violates the U.S. Constitution's guarantee of equal protection.

But attorneys representing the House's Bipartisan Legal Advisory Group counter that DOMA is subject to a lower level of court scrutiny because gays and lesbians don't meet the legal criteria for groups who receive heightened protection from discrimination. Under that lower standard, DOMA is constitutional, they argue.