"Marriage is a basic human right," Lewis said. "No government, federal or state, should tell people they cannot marry."

But Rep. Steve King, R-Iowa, said that repeal of the Defense of Marriage Act would devalue marriage. Those who claim they cannot choose who they fall in love with could make the same argument to justify polygamy, he said.

A handful of states and the District of Columbia issue marriage licenses to same-sex couples. New York will soon join Connecticut, Iowa, Massachusetts, New Hampshire and Vermont on that list.

But participants in same-sex marriages said they are still discriminated against because they cannot accrue the federal benefits that heterosexual couples receive as a result of marriage.

For example, Andrew Sorbo of Connecticut, said that when he retired as a teacher, he had no alternative except to pay for health insurance at a much higher cost that if he could have been covered under his spouse's plan. He said that the federal law exacts a financial toll and an emotional one.

"It's an insult to our dignity and our sense of equality," Sorbo said.

Witnesses speaking in favor of current law noted that many Democratic lawmakers in the hearing room voted for the Defense of Marriage Act 15 years ago. They said those votes helped make the case that the law was designed to protect traditional marriage rather than to discriminate.

Sen. Dick Durbin, D-Ill., citing President Abraham Lincoln in explaining why he now supports repeal, said he would rather be right some of the time than wrong all of the time.

Tom Minnery, senior vice president of the advocacy group Focus on the Family, argued that children fare best when living with their own married mother and father. He said in his written testimony that new family forms has largely served to diminish the well-being of children, women, men and society at large.

"I never thought I would have to defend traditional marriage," said Sen. Charles Grassley, R-Iowa. "It's been the foundation of society for 6,000 years."

The proponents of repeal acknowledge they have a tough fight getting enough votes to make it happen. No Republicans have signed on to legislation sponsored by Sen. Dianne Feinstein, D-Calif., that would repeal the Defense of Marriage Act.