"I want to choose the person who will make medical decisions on my behalf. But unfortunately for me, and thousands of gay Marylanders like me, that choice is not currently a fundamental right offered in Maryland's law," she said.

Ms. Kaiser was surrounded by relatives, her parents, aunts, friends and her rabbi, who she said were "110 percent" behind her.

The Maryland legislature has two other openly gay lawmakers: Delegate Maggie McIntosh, who chairs the Environmental Matters Committee and Delegate Richard Madeleno. Ms. McIntosh is from Baltimore city, Mr. Madeleno a Montgomery County legislator. Both are Democrats.

Members of the committee were surprised by the announcement. Delegate Rick Weldon, R-Frederick, was one of them.

"If it was grandstanding, it was pretty good grandstanding," Mr. Weldon said after the hearing.

About a dozen people took more than 90 minutes to testify on the bill, sponsored by Delegate John Hurson, D-Montgomery, the chairman of the House health panel.

A California man described how his partner died in a Baltimore hospital after surgery. Although the man had power of attorney for his partner, he was excluded from his bedside while other relatives weren't.

"Delegate Kaiser gave clear and compelling testimony, but the stories told by partners who were denied access to a bedside as their partner passed away makes the case more effectively," Mr. Weldon said.

Mr. Madeleno was in the audience as Ms. Kaiser spoke.

Her declaration "helps expand everyone's understanding of gays and lesbians in the state of Maryland," he said. "There's a lot of stereotypes about who we are and how we behave."

But he emphasized the substance of the bill was important also. It should be understood, he said, "how difficult it is to piece together the legal benefits of marriage through wills and power of attorneys and advance directives, and those sort of documents that even then wind up not being recognized."

Ms. Kaiser said she could not stand by during the ongoing gay marriage debate and hoped coming out as a lesbian in the General Assembly would help humanize the issue.

A bill sponsored by Delegate Emmett Burns Jr., D-Baltimore County, would declare that same sex marriages legal in other states or countries would be declared invalid in Maryland. The bill would also declare same sex marriages "against the policy of this state."

Delegate Charles Boutin, R-Harford, seeks to change the state constitution to limit marriage to unions between a man and a woman.

"When I see the attacks on gay marriage and civil unions and the vituperous attacks and the unfair comments, and the hate that is out there with so many people, and the misunderstanding I thought that I can't let that go," Ms. Kaiser said in an interview after her testimony.

She considered how her decision would affect her constituency, she said. The issue of her sexual orientation never came up during her campaign. She became a Democrat at age 7, in 1975, a time she said when civil rights and equal rights were at the forefront of debate.

"I'm hoping that it won't be a problem with my constituency, but at the same time I wasn't going to let that stop me," Ms. Kaiser said. She was elected in 2002.

She said she hoped her announcement put a more human face on the gay rights debate, and a more personal side to see three openly gay legislators for those who may be on the fence over the issue.

"I think it's a surprise to many people and I hope it breaks some of the stereotypes also," Ms. Kaiser said.

She is not in a relationship now, she said.

As Ms. Kaiser was giving her interview in front of reporters, Mr. Madeleno strode past. Health and Government Operations members were surprised by her testimony, he said.

"They had no idea you were Jewish," he joked.