Legal conflicts to take years to develop, some analysts say

"There will not be one quick answer; it will be a patchwork," as it was when states made different changes to divorce laws a generation ago, said Evan Wolfson, executive director of Freedom to Marry, a New York-based group that promotes same-sex marriage.

"It will take a couple of years of litigation to see what all this means," said Jay Alan Sekulow, chief counsel for the American Center for Law and Justice, a Virginia-based group that strongly opposes same-sex marriage. "There is not one quick answer and not necessarily one answer."

Because civil marriage is defined by the laws of individual states, the interstate impact of Massachusetts gay marriages probably will not be worked out through a highly visible test of whether there is a national constitutional right to such marriages, but through challenges to various rights that go with being married, analysts said.

They said they anticipated a series of legal contests, for instance, over a claim for marital benefits, the right to make medical decisions or a hospital visit, and the right to adopt a child.

Legal conflict is almost sure to develop on whether a gay marriage formalized in Massachusetts is entitled to respect in another state, say, for example, in the 37 states that have a policy against recognizing such marriages. "The Constitution either allows states to pick and choose which marriages they will respect or not," Wolfson commented. The outcome, he said, would not depend upon what an individual state may prefer or even what Congress may have desired when it enacted in 1996 a national law giving states power to refuse to respect gay marriages performed elsewhere.

"The first battleground," Sekulow said, "will be challenges to the constitutionality of the defense-of-marriage laws," the name given to the 1996 federal statute and to the 37 state statutes or constitutional clauses. That argument will be based on the Constitution's "full faith and credit" clause, he said.

That clause requires a state to bestow "full faith and credit" on one another's "public acts, records, and judicial proceedings," phrases that the Supreme Court has seldom interpreted. The phrase is carried out by a federal law that dates to 1790, passed by the nation's first Congress. The 1996 federal law goes beyond that early law and attempts to confer on states the explicit authority to refuse to accept gay marriages from other states.

Shari A. Levitan, a lawyer with the Boston firm of Holland & Knight, said the Supreme Judicial Court ruling will set up a direct conflict with that 1996 statute. "It's the first time that there's truly been a test like this," she said.

Gary Owen Todd, who is cochairman of the family law section of the Boston Bar Association, predicted that a clause in a state constitution would legally justify not recognizing a gay marriage in Massachusetts.

"I would suggest, in the short term, this ruling will not be recognized in a state that has amended its constitution to define marriage as between a man and a woman," he said.

But if a gay couple married with a Massachusetts license is denied rights based on the nature of their marriage, then a constitutional dispute would probably unfold.

Harvard law professor Laurence H. Tribe, a specialist in constitutional law, outlined what the arguments are likely to be in that circumstance.

One, he said, would be that a refusal to recognize a gay marriage is a denial of the Constitution's guarantee of legal equality, because opposite-sex marriages are respected, and another would be that the refusal interferes with the right to make private choices about how one lives life.

If a state responds by relying upon the federal defense-of-marriage law, Tribe said, the argument will then be made that Congress did not have the authority to give states that power, or, even if it did have that authority, that it acted unconstitutionally by interfering with the gay couple's right to equality, freedom of travel, and equal legal protection.

"I would think that sequence of events is so obviously predictable that it is very likely to be set in train over the next five years," Tribe said.

Denniston reported from Washington; Lewis, from Boston.