HELENA — An attorney for six gay couples seeking the same legal protections as married pairs asked a judge Tuesday to order Montana to establish civil unions, domestic partnerships or another system that ensures they're not denied those rights.

District Judge Jeffrey Sherlock heard arguments in the first court hearing of what is likely to be a lengthy legal process that will ultimately be decided years from now by the state Supreme Court.

"It's a journey of 1,000 miles and we're taking the first few steps," said plaintiff Mike Long.

Long and the other plaintiffs say they aren't asking for the right to marry, but they want to be able to make decisions about their families' health care, inheritance and burial, and have the ability to file joint tax returns, among other issues.

They say they have been denied those rights in violation of the state constitution's equal protection and privacy clauses. They asked Sherlock to grant an injunction and require the state to create the statutory framework to give them those protections.

"You don't get to deny those rights based on a policy that infringes on the Montana Constitution," said Bozeman attorney James Goetz, who spoke for the plaintiffs Tuesday.

The question appears to hinge in part on how the Montana Constitution's marriage amendment, which defines marriage as being between a man and a woman, is interpreted.

State solicitor Anthony Johnstone argued that Montana can't extend spousal benefits to gay couples because those benefits are limited to married couples by definition.

"Montana law provides spousal benefits to spouses and only spouses," Johnstone said.

The marriage amendment, which Montana voters approved in 2004, coupled with the separation of legislative and judicial powers, means Sherlock should dismiss the lawsuit, Johnstone said.

The state Legislature is free to create a new, separate class for couples regardless of sexual orientation, he said. But that's a policy choice for the state to make, not something that can be mandated by the court, he said.

Goetz said that undermines the state's case — either the constitutional amendment prohibits the extension of benefits to gay couples or it doesn't, but the state can't have it both ways.

Another question is whether gay couples in a committed relationship are similarly situated to married couples, which is the basis for claiming the gay couples face discrimination under the constitution's equal-protection clause.

Sherlock said gay couples in committed relationships face many of the same duties of married couples, such as bills to pay and children to care for.

"Doesn't that put them in the same boat as people who are married?" the judge asked.

No, Johnstone replied. The two groups are separate classes and that's what the people of Montana meant when they approved the marriage amendment, he said.

Goetz said the marriage amendment and the equal-protection clause can be reconciled. A similar case was decided in New Jersey in 2006 in which that state's Supreme Court ruled that same-sex marriage is not a constitutional right, he said.

But the court ordered New Jersey lawmakers to create a law that gives gay couples the same rights and benefits enjoyed by heterosexual couples, Goetz said. The Legislature legalized domestic partnerships as a result.

The plaintiffs want to see a similar result in Montana.

"The protections that we're after are basic protections allowed to any couple in a committed relationship," said Gary Stallings, who has been with partner Rick Wagner for 21 years. "I don't think you'll find a couple more committed than Rick and I are to each other, and I think something should be allowed about that."

The other plaintiffs are Jan Donaldson and Mary Anne Guggenheim, of Helena; Kellie Gibson and Denise Boettcher, of Laurel; Nancy Owens and M.J. Williams, of Basin; Long and Rich Parker, of Bozeman; and Stacey Haugland and Mary Leslie, of Bozeman.

Originally there were 14 plaintiffs, but Casey Charles and David Wilson, of Missoula, dropped out of the lawsuit for personal reasons, the ACLU said.