Though some members of the Republican party have been moving rapidly to support LGBT rights and in particular equal marriage, the shift has been far from universal. And as my colleague David Nakamura reported the other day, that could pose a problem for immigration reform. Senate Judiciary Committee chairman Patrick Leahy (D-Vt.) is expected to introduce the Uniting American Families Act as an amendment to the immigration bill. That's a bill that's been kicking around since at least 2000 that would extend the automatic green card privilege granted to heterosexual spouses to the foreign-born partners of American gays, lesbians and bisexuals.

That idea has some very limited Republican support — Sen. Susan Collins (Maine) and Reps. Richard Hanna (N.Y.) and Charles Dent (Pa.) are co-sponsors of the respective Senate and House bills this Congress. But others in the caucus are skeptical. Sen. Marco Rubio of Florida, perhaps the main Republican shepherd of the immigration bill in the Senate, has warned the amendment could kill the bill, saying that "if that issue is injected into this bill, this bill will fail. It will not have the support. It will not have my support." Sen. Jeff Flake (R-Ariz.) told the New York Times the provision was a "deal-breaker for most Republicans."

Leahy, of course, disputes that, telling Politico, "It's not going to kill the bill." Jonathan Rauch, a leading gay libertarian, supports bringing up the amendment if for nothing else than as a test of Republicans. "Just how much electoral support and moral standing does the GOP want to give up to affirm its hostility to homosexuals?" Rauch asks.

But there's an interesting wrinkle in the issue that's gotten surprisingly little attention. The law that's standing in the way of allowing same-sex spouses who get married in one of the 10 states (plus Washington, D.C.) where same-sex is legal to get green cards is the Defense of Marriage Act. DOMA bans federal recognition of same-sex marriages. But the law is also before the Supreme Court at the moment, and there's a real chance that a majority will rule it to unconstitutional.

If that happens, legally married LGBT couples will be able to petition for green cards, the same as any other married couple. At least that's the interpretation of Paul Smith, a partner at Jenner & Block and arguably the leading gay rights litigator in the country (he won Lawrence v. Texas, overturning state bans on gay sex). Smith e-mails, "My understanding is that the elimination of DOMA would by itself mean that all binational married couples would have the same rights, whether same sex or not."

Steve Ralls, director of communications at Immigration Equality (IE), an advocacy group that works on behalf of binational same-sex couples, agrees. "The precedent in immigration law is that marriages are recognized based on the state of celebration, not the state of domicile. If it's valid where performed, it's valid for immigration," Ralls says. "A couple in Virginia could travel to the District, get married and then petition for their green card." IE has its own case pending in federal court, but its outcome is directly pegged to the case before the Supreme Court right now, United States v. Windsor. If Edith Windsor, the plaintiff in that case who is challenging DOMA, wins, then so does IE.

But it's possible that the Windsor ruling will not be that clean. The Supreme Court could, for instance, rule that DOMA's defenders don't have standing, and thus that it's void, but only in the area covered by the appeals court that ruled it unconstitutional (basically, Connecticut, New York and Vermont). What that means for immigration is much less clear. Also, Ralls notes that unlike the Uniting American Families Act, even a full overturning of DOMA would do basically nothing for couples with civil unions or domestic partnerships in states like New Jersey or California. If, for whatever reason, they can't travel to a state with same-sex marriage, overturning DOMA does nothing for them.

Ralls notes that his organization still supports including the Uniting American Families Act in a comprehensive immigration reform bill. But if DOMA dies this spring, that could give Senate Democrats a way to save face while not alienating Republican supporters by adding that provision to the bill.

Update: Lavi Soloway, a immigration attorney who helped draft the Uniting American Families Act, notes that an overturn of DOMA would mean that no one would qualify for the new "partner" category the act creates, as the act only applies to those who cannot have their marriages recognized by the federal government.

"From its inception, the Uniting American Families Act was designed specifically to remedy the harm caused by DOMA to lesbian and gay binational couples," he writes. "It achieves this goal by adding the category of 'permanent partner' to family unification provisions of our immigration law. It defines 'permanent partners' in such a way that the permanent partner category exists as long as marriages of same-sex couples cannot be recognized for immigration purposes because of DOMA."