New York ? Gay-rights activists in the United States liken their mood to that of Germans as the Berlin Wall crumbled. Neighboring Canada has just decided to legalize same-sex marriage, and the activists have high hopes that Massachusetts’ supreme court will take a similar step within a few weeks.

They predict litigation will spread to other states, and the end result — perhaps after years of lawsuits and legislative battles — will be legalized gay marriage nationwide.

“People are going to look back 30 years from now, and say, ‘What were we thinking? Why would we deny committed couples the protections of marriage?”‘ said Evan Wolfson, a gay-rights lawyer who heads the advocacy group Freedom to Marry.

To opponents of gay marriage, however, the American family is what’s now in danger of crumbling.

“Unless the American people rise up to defend this indispensable institution, we could lose marriage in a very short time,” said Ken Connor, president of the Washington-based Family Research Council.

Roman Catholic leaders in Massachusetts, in a recent statement to parishioners, said a high court ruling redefining marriage “will have devastating consequences here and nationally.”

“Throughout all history, marriage has been heterosexual,” said an another statement endorsed by the Catholic hierarchy. “It cannot mean everything, or it will ultimately mean nothing.”

The Massachusetts case involves a lawsuit filed by seven same-sex couples who sought marriage licenses in 2001. When they were rebuffed, they sued the state Department of Public Health.

The case is now before the Massachusetts Supreme Judicial Court. The state’s lawyers have argued that only the Legislature has the authority to redefine marriage; the plaintiffs say same-sex couples and their children deserve the same legal protections afforded to heterosexual married couples.

Toronto City Councilman Kyle Rae, center, and his spouse, Mark Reid, left, celebrate after their wedding ceremony in Toronto, Canada. The pair married Friday after the federal government announced earlier last week that Canada's marriage laws would be rewritten to include unions of gays and lesbians. Canada will be the third nation, after Belgium and the Netherlands, to legalize gay marriage.

A similar lawsuit has been filed in New Jersey, where a judge will hear arguments this week on the state’s attempt to dismiss it.

Defining a marriage union

On both sides of the debate, advocacy groups expect that gay couples who marry in Canada — or any state that legalizes gay marriage — will attempt to have their marriages recognized elsewhere.

However, 37 states and the federal government have adopted Defense of Marriage Acts in recent years, defining marriage as a union between a man and a woman. Many are expecting lawsuits.

Some opponents of gay marriage say their best hope, rather than fight state-by-state court battles, would be to enshrine the “man and woman” definition of marriage in the U.S. Constitution. An amendment to accomplish that goal has been introduced in Congress; it would need two-thirds approval in both the chambers and then be ratified by at least 38 states.

Decision trigger

Matt Daniels, head of the Alliance for Marriage, which has championed the proposed amendment, believes his cause will gain momentum because of the Canadian policy change and what he expects to be a Massachusetts ruling in favor of gay marriage.

“We’re all sitting on the edge of our seats, waiting for the event in the courts that will push this issue to the forefront of public consciousness,” Daniels said. “The real trigger won’t be the Massachusetts decision, but rather the effort to export that decision.”

Daniels hopes elected officials will resist efforts to have Canadian same-sex marriages recognized in the United States.

“The American people should determine the future of marriage in this country,” he said. “It shouldn’t be a foreign government, it shouldn’t be a foreign court.”

Relying on home

Cindy Meneghin and Maureen Kilian, partners since a high school romance 28 years ago, also don’t want to rely on foreign laws. They want to be married in their home state of New Jersey, and are among the couples who filed the gay-marriage lawsuit there last year.

“The ruling in Canada gives us hope,” Kilian said. “But we want to wait and see it through in New Jersey. Our home is here, our families are here.”

Kilian works part-time as an administrator for an Episcopal church; Meneghin works at Montclair State University. They share a home in Butler, N.J., with a 10-year-old son and 8-year-old daughter.

“To say we were beaming like crazy when we heard the news about Canada is an understatement,” said Meneghin, 45. “When people see Canada doesn’t fall out of the Western Hemisphere, then suddenly people will start to say, ‘What’s the big deal?”‘

Canada will be the third nation, after Belgium and the Netherlands, to legalize gay marriage, but its proximity and lack of a residency requirement make it the best option for American same-sex couples. But those who marry there will face unknowns when they return, Wolfson said.

“They will encounter discrimination, they will face legal uncertainty, but they also will find, in many instances, respect and legal acknowledgment,” he said. “Courts will struggle with this, just as business and individuals are struggling with it. It will percolate for some time.”