WASHINGTON – The Supreme Court yesterday declined to hear a challenge to a landmark Massachusetts court decision that legalized gay marriage and spurred a nationwide movement for a federal constitutional amendment to preserve traditional unions.

The challenge did not take issue with the reasoning behind the 2003 Goodridge decision from Massachusett’s Supreme Judicial Court, which held that the state’s marriage laws were discriminatory, contrary to the state constitution. Instead, 11 Massachusetts legislators and the vice president of the Catholic Action League, Robert Largess, attacked the very authority of the court to expand the definition of marriage.

The plaintiffs made the unusual argument that the state court had “usurped” the power of the Legislature with its ruling, and violated a clause of the federal Constitution that guarantees to the people of each state a “republican form of government.”

The top court declined to hear the case without comment. But two lower federal courts gave copious explanations of why they were not persuaded by the group’s arguments.

Last May, the District Court judge, Joseph Tauro, declined to issue an injunction against the enforcement of the Goodridge decision. He rejected the group’s arguments that the state court did not have jurisdiction over matters of marriage and divorce, finding that the Legislature had transferred the subject matter to the court as early as 1785 and 1836.

Judge Tauro also rejected the allegation that the court had “usurped” power, finding that the gay marriage ruling “was not a legislative act.”

The following day, a three-judge panel of the U.S. Court of Appeals for the 1st Circuit also denied the injunction. They wrote that claims under the so-called Guarantee Clause of the federal Constitution are political questions beyond the power of courts in all but extreme cases.

Unless the state court had established permanent marital law or declared the Commonwealth of Massachusetts to be a monarchy, the panel would not involve itself. Further, federal courts must defer to the highest state courts for controlling interpretations of state law, the appeals judges wrote.

In a final decision in June, the appellate panel added that opponents of gay marriage have the option of amending the state constitution. An effort to pass such an amendment is underway in Massachusetts.

President Bush said he will push for a federal constitutional amendment in his second term.

The suit was “a weak and misguided legal effort from right-wing anti-gay groups that never really stood much chance of being heard at the Supreme Court,” said David Buckel, the director of the marriage project at Lambda Legal, a pro-gay marriage advocacy group.

But Matthew Staver, the president and general counsel of Liberty Counsel, a legal group representing the plaintiffs, said yesterday’s decision highlighted the need for an amendment to the American Constitution to define marriage as the union of one man and one woman.

“The battle is far from over. The Constitution should protect the citizens of Massachusetts from their own state Supreme Court’s usurpation of power,” he said.