The White House was mum Friday about plans to appeal a Massachusetts gay marriage ruling, saying only that the administration is “reviewing the decision.”

The decision handed down Thursday by U.S. District Court Judge Joseph L. Tauro says the Defense of Marriage Act (DOMA) violates the Fourteenth Amendment's equal protection guarantee.

The 1996 law signed by President Bill Clinton defines marriage as a heterosexual union for federal agencies and allows states to ignore the legal marriages of gay couples performed outside their borders.

The act “plainly encroaches” on a state's right to define marriage, Tauro wrote.

“Congress undertook this classification for the one purpose that lies entirely outside the legislative bounds, to disadvantage a group of which it disapproves. And such a classification the Constitution clearly will not permit,” he added.

The ruling's narrow scope leaves much of the law unscathed and applies only in Massachusetts.

Plaintiffs had argued that the law denies legally married gay couples access to federal benefits.

President Barack Obama called DOMA “abhorrent” and called for its legislative repeal while campaigning. But a repeal bill sponsored by New York Congressman Jerrold Nadler has attracted little interest and only 112 co-sponsors since its introduction. And the president has yet to directly mention the Respect for Marriage Act, Rep. Nadler's bill.

The Department of Justice, which has said it is obliged to defend the laws approved by Congress, has not announced whether it will appeal the ruling. It has 14 days to decide before the ruling goes into effect.

The decision pushes the administration to walk a tight rope. Tauro's ruling remains limited to Massachusetts, but in appealing to a higher court with a broader jurisdiction the government risks spreading the ruling's impact. Left unchallenged, however, the ruling could encourage other states where gay marriage is legal to challenge the federal law. Gay marriage is legal in Vermont, Connecticut, Iowa, New Hampshire and the District of Columbia.

Gay marriage opponents have suggested the administration's defense of the law was weak.