NEW YORK - State lawyers defended Gov. David Paterson's move to recognize out-of-state gay marriages, asking a judge on Thursday to dismiss a Christian legal group's claim that the governor overstepped his authority.

The case is the first direct legal challenge to arise since Paterson's administration told state agencies in May to extend spousal rights to same-sex couples legally wed elsewhere. A ruling is expected within a month.

The Bronx court fight comes as thousands of gay New York couples are expected to take advantage of a new Massachusetts law allowing them to wed there.

The Christian group, the Alliance Defense Fund, emerged from state Supreme Court Judge Lucy Billings' courtroom “hopeful,” attorney Brian Raum said. Paterson spokeswoman Erin Duggan said the governor's office was “confident in the merits of our legal position.”

Same-sex couples cannot marry in New York, and the state's highest court has said only the Legislature could change that. But Paterson's counsel told state agencies in May that a recent state appellate court ruling required them to recognize gay marriages legally performed elsewhere or risk discrimination lawsuits.

The Scottsdale, Ariz.-based Alliance Defense Fund opposes gay marriage in general, Raum said. But its case against Paterson centers on constitutional powers, not the policy itself.

The alliance says the question of recognizing out-of-state gay marriages lies on the Legislature's legal turf, not the governor's. And the group notes that the Legislature has not moved to recognize the unions.

“(Paterson) is without legal authority to effect such a fundamental and expansive change to the institution of marriage,” the group wrote in legal papers filed on behalf of several Republican state senators and other petitioners, who are seeking to stop state agencies from implementing the memo's provisions.

The Democratic governor's camp, however, notes that lawmakers have not barred recognition of same-sex weddings conducted elsewhere, despite repeated proposals to do so.

The alliance's arguments don't “make any showing that the challenged memorandum is contrary to the law of New York,” state Attorney General Andrew Cuomo's office wrote, acting as the governor's lawyers.

The alliance is involved in numerous cases that concern gay marriage, abortion, school prayer and other social issues. Before filing its latest suit against Paterson, it already had several ongoing cases against New York's state government over attempts to extend spousal rights to gay couples.

Massachusetts and California are the only U.S. states that allow gay marriages. Some other states let same-sex couples enter into civil unions offering some of marriage's legal advantages.

Out-of-state gay couples were unable to marry in Massachusetts until July 31, when Gov. Deval Patrick signed a bill repealing a 1913 law that barred any marriage that would be illegal in a couple's home state.