OLYMPIA, Wash. (AP) – Tom Richardson and Salvador Valenzuela first marked their commitment to each other with a city domestic partnership in Seattle. When Massachusetts became the first state to allow same-sex marriage, they married, and hyphenated their last names.

Now back in Washington state, the Richardson-Valenzuelas plan to register for a state domestic partnership here, taking advantage of the new law that takes effect Monday and gives same-sex couples some of the benefits that married heterosexual couples enjoy.

The only problem is that by doing so, they risk getting Salvador, a Mexican national, deported, because registering could jeopardize the temporary tourist visas he uses to enter the country.

“It’s really important for our relationship to be recognized,” said Tom Richardson-Valenzuela, who said they both realize that the immigration laws may catch up with them. “We are a legitimate couple. If we have to leave the United States, as much as we don’t want to leave the country, we will.”

Gay and lesbian advocacy groups are urging couples like the Richardson-Valenzuelas to think twice before registering. Couples where one or both members are either foreign nationals or members of the military are at risk if they acknowledge their relationships, not only in Washington state, but in all states that provide legal recognition to same-sex couples.

“Be very, very careful and seek legal advice before seeking a domestic partnership,” said Lara Schwartz, the legal director for the Human Rights Campaign in Washington, D.C.

Because immigration law does not recognize same-sex couples, an American citizen would not be able to sponsor a partner on a temporary visa, and in some cases registering for a domestic partnership could jeopardize a foreign national’s status. In the case of military couples, it could violate the “Don’t Ask, Don’t Tell” law and jeopardize their careers.

The new state law creates a domestic partnership registry with the state, and will provide enhanced rights for same-sex couples, including hospital visitation rights, the ability to authorize autopsies and organ donations and inheritance rights when there is no will.

The new domestic partnership law “is a huge step for marriage equality in the state,” said Connie Watts, executive director of Equal Rights Washington. “But as you start looking at it closely you’ll see we have a long way to go.”

Watts said that since both immigration laws and “Don’t Ask, Don’t Tell” are federal issues, there’s nothing that a state law can do to change these couples’ situations.

“When it comes to gay and lesbian issues, change is coming at the state level,” said state Sen. Ed Murray, sponsor of the domestic partnership law and one of five openly gay lawmakers in the state Legislature.

“Don’t Ask, Don’t Tell” passed in 1994. The law allows gays and lesbians to serve if they keep their sexual orientation private, but requires the military to discharge those who acknowledge they are gay.

“The domestic partnership registries are public documents that the Department of Defense has access to,” said Steve Ralls, a spokesperson for the Washington, D.C.-based Service Members Legal Defense Network, a legal aid and advocacy group for gay and lesbian members of the military.

Ralls said he is not aware of any cases where service members were kicked out of the military because of domestic partnerships or civil unions in other states. But that’s likely because most don’t register, he said.

“The risk is simply too much,” he said. “The overwhelming majority decide not to do that registration until their military service is complete.”

Michael, of Vancouver, is retired from the Navy and is holding off on a domestic partnership with his partner of 10 years, who is currently in the Navy Reserves.

“It’s just one of those things,” said Michael, 42, who asked that his last name be withheld to protect his partner’s identity. “It probably comes from the way you get accustomed to living in the military. It just doesn’t come up.”

Approximately four percent of the gay and lesbian couples in the state – at least 700 couples – include one foreign national, according to a 2004 report prepared for Immigration Equality, a New York-based advocacy group.

Schwartz said that most temporary visas are granted after the applicant promises they intend to return to their home country.

“Once you enter into a legal partnership, be it a marriage or domestic partnership, you have really undermined that statement,” she said.

Tom Richardson-Valenzuela said they were fully aware of the risks to Salvador’s visa status – he travels regularly to the United States on a tourist visa – when they registered for the Seattle domestic partnership, and again when they married in 2005.

But because their marriage is not recognized in Washington state, the couple want to register as domestic partners in order to get some of the rights and benefits that they would get if they were still in Massachusetts.

“I can’t tell you how important that is,” he said.

To be registered, couples must share a home, not be married or in a domestic relationship with someone else, and be at least 18.

In a provision similar to California law, unmarried, heterosexual senior couples are also eligible for domestic partnerships if one partner is at least 62. Lawmakers said that provision was included to help seniors who are at risk of losing pension rights and Social Security benefits if they remarry.

Couples can register in person with the Secretary of State in Olympia, though many are expected to download the form from the Web site and mail it in.

The new law takes effect a year after the state Supreme Court upheld Washington’s ban on same-sex marriage in a 5-4 decision, ruling that state lawmakers were justified in passing the 1998 Defense of Marriage Act, which restricts marriage to unions between a man and woman.

Several other states have approved either civil unions or domestic partnerships for same-sex couples, including Connecticut, Vermont, New Hampshire, New Jersey, Maine, California and Oregon. Hawaii extends certain spousal rights to same-sex couples and cohabiting heterosexual pairs. Only Massachusetts allows same-sex couples to marry.

“I do celebrate the fact that here in Washington we’re moving forward with domestic partnerships,” said Michael, the partner of the Navy reservist. “The key to me is that it’s offering protections for people while we continue to fight for full marriage equality.

“It doesn’t help me a bit. But it does give me hope.”