EATTLE, July 5 — Spurred on by the Supreme Court's landmark ruling decriminalizing gay sexual conduct, both sides in the debate over gay rights are vowing an intense state-by-state fight over deeply polarizing questions, foremost among them whether gays should be allowed to marry.

Even with most legislatures out of session until early next year, lively debates are already taking shape across the country, from Hawaii to Connecticut, Oregon to Alabama to Massachusetts. Potentially fierce battles over marriage and other rights loom in dozens of statehouses and state courts, as social conservatives — including the Senate majority leader, Bill Frist of Tennessee — try to breathe new life into a proposed constitutional amendment that would effectively ban gay marriage.

In dozens of interviews this week, activists, pundits on both sides and legal scholars from across the political spectrum said that with the Supreme Court's June 26 ruling in Lawrence v. Texas, the country was now at a revolutionary moment akin to the aftermath of the court decisions in Brown v. the Board of Education, which banned school segregation, and Roe v. Wade, which legalized abortion.

"The right wing is really galvanized by this, throwing down the barricades," said William Rubenstein, a law professor at the University of California at Los Angeles and the faculty chairman of the Williams project on sexual orientation law.

At the same time, he said, "Gay rights activists are excited and want to go the next step. On the one hand the Lawrence decision gives advocates an enormous weapon in their arsenal, and at the same time it will mobilize opponents of same-sex marriage in ways we haven't seen."

Most agreed that the question of whether the United States will allow gays to marry would become the next major focus of both the gay rights movement and of social conservatives, now that the Supreme Court has decriminalized gay sexual conduct, effectively removing what has been used by many states as the basis for discrimination on a wide array of civil rights questions.

A decision last month by Ontario, Canada, to extend marriage rights to same-sex couples, which is expected to go into effect for the whole country by the end of the year and make Canada the third country after the Netherlands and Belgium to allow gays to marry, is also bound to put the gay marriage question on the political front burner here.

"America has hit a tipping point in which fair-minded people now support equality and inclusion for gay people and most Americans are ready to accept marriage," said Evan Wolfson of Freedom to Marry, an advocacy group in New York.

"We are in a Brown v. Board of Education moment right now," Mr. Wolfson said. "The Supreme Court has said in the strongest possible terms that love and intimacy and family have deep constitutional protection for all Americans and that gay people have an equal right to participate. This gives us a tremendous tool for moving forward to end the discrimination."

"At the same time," he added, "it is important to remember what came after Brown: major legal challenges and acts of courage but also fierce resistance."

Glenn Stanton, senior analyst for marriage and sexuality at Focus on the Family, a national organization opposed to gay rights, agreed there would be resistance.

"I think that what will happen is that states will be seeking to say, `You know what? Don't bring any of that stuff here,' " he said. "We know what we want, we know what marriage is, and we know what sexual relationships are. They will be asking how they can protect life as they know it, rather than life as the Supreme Court tells them it's going to be."

State gay rights organizations and social conservative groups are preparing for legislative and court fights.

"These are the first shots in the largest battle in the culture wars since Roe v. Wade," said Brian Brown, executive director of the Family Institute of Connecticut, a conservative group. "The people of Connecticut are not going to stand for this."

He added, "Politicians in Connecticut will have nowhere to hide. You'll have to choose a side. Either you support traditional marriage or you radically redefine it, it's as simple as that."