Lawyers for five gay couples who were denied marriage licenses in New York City are signaling the legal arguments they will make this spring before the state’s highest court, filing a brief yesterday that says refusing weddings to same-sex couples violates “bedrock” guarantees under the state constitution and is blatantly discriminatory.

The arguments, which were outlined by Lambda Legal, the gay rights firm representing the couples, in a brief to the court of appeals, offer the first look into the final phase of a lawsuit that has been in the works for nearly two years.

In February 2005, a state Supreme Court justice, Doris Ling-Cohan, ruled that banning the marriages violated the state constitution. That decision was appealed by the city and struck down by the Supreme Court’s Appellate Division in December before the court of appeals agreed to hear the case.

“We believe that we have a constitutional right in New York State to marry the person we’re in love with,” said the executive director of a gay rights group, the Empire State Pride Agenda, Alan Van Capelle. “The lower court ruled in our favor, the mid-level court ruled against us, so this court is sort of the tiebreaker.”

In its 119-page brief, Lambda argued that denying same-sex couples the right to wed violates “bedrock guarantees of due process and equal protection” under the state’s constitution.

It says that marriage is a fundamental constitutional right and that equal protection laws guard against “unjustified discrimination based on irrelevant characteristics.” It also says that denying the marriages serves no overarching public interest and perpetuates a traditional view that violates equal protection.

The brief also says that New York began “dismantling the entrenched tradition of coverture” in the mid-19th century in favor of “equality between the sexes and enabling each couple to chart its own course.”

“They rested their analyses on the thinnest of reeds,” the brief states of opponents of court-ordered gay marriage.

The city has until March 24 to file its brief with the court, and while no date has been set yet, Lambda lawyers say they expect oral arguments to start in the spring.

Lambda’s brief details facts about each of the five relationships, including how many children they have, if any, where they live, where they work, and how they share most everything in their lives, including bank accounts.

One of the couples, Michael Elsasser and Douglas Robinson, raised two sons together. The boys, now 17 and 20, called Mr. Elsasser “Pop” and Mr. Robinson “Dad.” Another couple, Lauren Abrams and Donna Freeman-Tweed, has been together for eight years and have two sons whom Ms. Abrams conceived through artificial insemination. Ms. Freeman-Tweed adopted them several years ago, according to the brief.

“This is about real people who are not trying to make a point. They are just trying to be married,” the lead attorney on the case for Lambda, Susan Sommer, told The New York Sun. “This is not intended to and will not hurt anyone else’s marriage.”

The case pits the couples against New York City and has already proven politically tricky for Mayor Bloomberg, who has said that current law does not allow two people of the same sex to marry.

Mr. Bloomberg said last February that he supports gay marriage, but the city could not issue licenses without a ruling from the state’s highest court. Without that, he said, the city would risk having those marriages annulled through a legal challenge down the road similar to the one that overturned gay marriages performed in San Francisco in 2004. Mr. Bloomberg has also said he will lobby Albany to change the law if the court rules against the couples.

Yesterday the chief of the appeals division for Mr. Bloomberg’s Law Department, Leonard Koerner, said the city received the brief filed by Lambda Legal, and will evaluate it.

“As Mayor Bloomberg has stated, he supports same-sex marriages in New York State and measures that would authorize it,” Mr. Koerner said in a statement. “As the City’s briefs have set forth previously, the matter is more appropriately an issue for the State Legislature, not the courts.”

The issue of gay marriage has become a rallying call for both proponents and opponents nationwide, and cases are wending through courts in several states. Conservative groups, who have pushed Congress to support a federal ban on gay marriage in the past, have vowed to fight against it aggressively.

Yesterday the vice president for policy at the Family Research Council, Peter Sprigg, said it would be a grave mistake for anyone to tamper with the one-man, one-woman definition of marriage that has “served society for thousands of years.” He said it is not up to the courts to rewrite that law if they disagree with it.

To date, Massachusetts is the only state that has ruled in favor of gay marriage, while Connecticut and Vermont have legal civil unions, a step short of marriage.

Many following the issue will undoubtedly turn their attention to New York Court of Appeals once the oral arguments in the case get under way.

The dean of the College of Liberal Arts and Sciences at SUNY New Paltz, Gerald Benjamin – who said he favors civil unions, but not gay marriage – predicted that the Court of Appeals would rule against the couples. The court includes four of Governor Pataki’s appointees and three of Governor Cuomo’s.

The Pride Agenda and Lambda Legal are planning a statewide campaign to get their message out. Mr. Van Capelle said his group will spend between $500,000 and $1 million on advertising.