Washington (CNN) -- Sen. Dianne Feinstein, D-California, announced Tuesday a bill to repeal the federal law that defines marriage as a "legal union between one man and one woman as husband and wife" and that allows states to reject legal same sex marriages from other states.
The Defense of Marriage Act, or DOMA, passed both the House and the Senate in 1996.
Feinstein said she is one of only 14 senators who voted against the legislation at the time. "I thought even then, this is unconstitutional and wrong. Well, today it's unconstitutional, I believe, and wrong," she said in a news conference at the National Press Club in Washington.
She said her bill would "strike the Defense of Marriage Act from law and would free the government to allow for the same type of benefits they allow for married couples to also be applied to same-sex couples."
"Family law has been traditionally the preserve of state law," she said. "Therefore it varies from state to state and the federal government usually stays out of it." Marriage, divorce, adoption and inheritance are all under the purview of individual states, she noted, adding that the federal government is involved only in relation to marriage.
"Believe it or not, there are over 1,000 federal laws and protections that are afforded to married couples but are not afforded to legally married same-sex couples in any of the states that have approved same-sex marriage," she said.
Kathleen Cumiskey and Robin Garber were among three same-sex couples who joined Feinstein at the news conference. They said they traveled from New York's Staten Island with a stack of papers they take with them nearly everywhere.
The couple was married in Toronto, Canada, in 2006 and their home state of New York legally recognized their marriage in 2008. But when they travel across state lines, they said, they have to bring with them paperwork in case of an emergency.
"We traveled from New York City last night and had to bring with us our box of documents," Garber said holding up a marbled-cover box. "Wherever we go we need to be able to prove the legal documentation of our relationship. We need to be able to prove that we are legally responsible for each other, that we have the legal right to make decisions for each other."
She added, "We find it really incredible that we can travel halfway around the world -- we can go to Spain, we can go to Ireland, we can go to South Africa -- and have our marriage recognized and respected, but when we travel 15 miles from our own front door that is not the case and we need our box of documents."
Feinstein's repeal bill has gained 27 Democratic co-sponsors. She noted in the hallway after her remarks that there has been no Republican support for the bill. "I think it's a hard time because of the tea party and the ideological bent, but I think that's going to change," she said.
She added that the bill would have a hard time getting through the House were it pass in the Senate, but "we're in this for the long march, not just the short hop."
In February, President Barack Obama ordered the Justice Department to stop defending the constitutionality of the Defense of Marriage Act.
The Senate Judiciary committee will hold a hearing on the repeal bill Wednesday.