A major barrier to equality for gays and lesbians, Evans said, is the federal Defense of Marriage Act. That Clinton-era law defines marriage as the union of one man and one woman for the purpose of federal tax status and U.S. government benefits. It also said states do not have to recognize same-sex marriages sanctioned by other states.
DOMA, as the law is known, is now before the Supreme Court, and some believe it could be struck down by the time the high court ends its term in June.
But even if DOMA falls, Evans said, there are other reasons Maryland should keep domestic partner benefits.
"In other states, we are not truly equal yet," she said.
Evans, a lawyer, said 29 states have no laws preventing employers from discriminating against workers on the basis of sexual orientation. For people whose professional careers require them to move to more conservative states, she said, getting married under Maryland law could be risky.
"If I'm taking a new job in Kansas and I'm filling out a W-4 and I have to put marital status, I'm going to have to put 'married.' " She said. "That's going to trigger: 'Who is your spouse?' "
Differences in divorce laws from state to state also present a challenge, Evans said. Same-sex partners who wed here and move to another state could find themselves trapped in a failed marriage unless they move back to Maryland, which grants divorce to in-state residents only.
As long as such inequalities exist, she said, it is unlikely the courts would uphold a challenge to the state's existing domestic partner rules.
Evans said she's not saying gays and lesbians should be able to claim domestic partner status forever.
"There is absolutely going to be a time when we can do away with domestic partner benefits," she said.
But Del. Maggie McIntosh, an openly gay member of the General Assembly, said the time is now. McIntosh, a Baltimore Democrat who chairs a powerful House committee, said the administration is doing the right thing.
"In Maryland, we have a level playing field," she said. "Because we fought for equality, we got equality, we should now be embracing equality."
McIntosh, who married earlier this year under the new law, said she doubts many same-sex couples in domestic partnerships will rush to the courthouse just because of the policy change.
"Marrying somebody for their health insurance is a little bit of the wrong motivation," she said.
An earlier version of the story misstated the number of state employees who would be affected by the decision. The Baltimore Sun regrets the error.