Same-sex couples, in which one partner is a foreigner, have filed a lawsuit challenging a federal law that prevents them from getting a green card for their spouses, just ahead of the start of a related court battle that some predict could bring the issue of gay marriage to the Supreme Court.

The lawsuit, filed Monday on behalf of five binational gay couples, targets Section 3 of the Defense of Marriage Act (DOMA), which blocks federal benefits for same-sex couples — including the right of an American to sponsor their foreign spouse for a green card. The lawsuit claims that DOMA violates their constitutional right to equal protection.

“Our couples can’t just wait any longer … we’ve spent the past year working with the Obama administration to encourage them to place green card applications for gay and lesbian couples on hold until DOMA is struck down by the courts or repealed by Congress, and they have declined to do that,” said Rachel B. Tiven, executive director of Immigration Equality, which filed the lawsuit along with Paul, Weiss, Rifkind, Wharton & Garrison LLP.  “As a result, we really have no choice but to sue.”

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