BALTIMORE (AP) – The lawyer for 19 gay men and lesbians argued in circuit court that Maryland’s ban on same-sex marriages violates the guarantee of equal rights under the state constitution.

“There is no constitutionally permissible reason for this discrimination,” Kenneth Choe, an American Civil Liberties Union lawyer, told Judge Brooke M. Murdock. “It does not serve a rational or legitimate purpose of government.”

The 1973 law specifying that marriage is a union of one man and one woman was defended by the state attorney general’s office.

Assistant Attorney General Steven Sullivan appealed to Murdock not to interject the courts into what he said is a legislative prerogative. Approving marriage of same-sex couples would change “the essence of the institution as it has always existed,” he said.

After hearing more than an hour of arguments from opposing lawyers, Murdock said she would issue her decision in a written opinion, but did not say when the opinion would be ready.

Maryland and at least five other states – New York, New Jersey, California, Connecticut and Washington – have lawsuits pending challenging state prohibitions on same-sex marriages. A similar ban was struck down in Massachusetts, the only state where same-sex marriages are legal.

The Maryland suit was filed against court clerks in Prince George’s, St. Mary’s, Dorchester and Washington counties and Baltimore city. Regardless of which way Murdock rules, her decision is expected to be appealed to Maryland’s highest court, the Court of Appeals.

During the court session, Choe argued that there is no justification for the ban on same-sex marriages that would override the guarantee in the state constitution of equal treatment for all.

“It is undisputed in this case that gay and lesbian couples have long suffered grievous discrimination,” Choe said.

Banning same-sex marriages “does nothing to enhance the welfare of children of heterosexual couples but significantly diminishes the welfare of children of same-sex couples,” he said.

Arguing that there is no fundamental right to marriage guaranteed in the state constitution, Assistant Attorney General Robert Zarnoch said, “The issue of same-sex marriage is really, really a recent development. … Almost all states have laws prohibiting this kind of marriage.”

Outside the courthouse, Dan Furmansky, executive director of the gay rights organization Equality Maryland, said the plaintiffs are asking only for fairness and equal treatment.

“We’re not a radical group of people. We’re a group of ordinary citizens … who are trying to take care of our families,” he said. “We ask that you not stand in opposition to us just as we don’t stand in opposition to you.”

Takia Foskey, one of the plaintiffs, said when her partner, Jo Rabb, had emergency surgery, she had to sit in the hospital waiting room with no input into Rabb’s treatment. She would also like her 7-year-old son, who has asthma and a heart murmur, to have access to Rabb’s health insurance, a right that would be available to married couples, she said.

“It is very difficult to come up with the money for his medicine and his treatment,” Foskey said.

Across the street from the gay rights news conference, same-sex marriage opponents said they hope the judge will not intervene in what should be a legislative decision.

“Where do we want our laws made? On the House floor and the Senate floor,” said the Rev. Richard C. Bowers, chair of Defend Maryland Marriage.

Douglas Stiegler, who heads the Family Protection Lobby and the Association of Maryland Families, said opponents of same-sex marriage will continue to lobby the General Assembly to amend the constitution even if Murdock rules that the existing law is valid.