The California Supreme Court ruled Thursday that an illegal immigrant can join the bar and begin to practice law in that state, granting a major symbolic victory to immigrant rights advocates who say it’s a step on the path to equal treatment in employment law.

Rebuffing the Obama administration’s arguments, the justices unanimously decided in favor of Sergio C. Garcia, an illegal immigrant who was twice brought across the border illegally by his parents, eventually earned a law degree from a California school and has been trying to join the bar for years.

Chief Justice Tani Cantil-Sakauye said state legislation signed last year by Gov. Jerry Brown removed the final barriers and Mr. Garcia can be licensed, even though he is not in the country legally.

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“We conclude that the fact that an undocumented immigrant’s presence in this country violates federal statutes is not itself a sufficient or persuasive basis for denying undocumented immigrants, as a class, admission to the state bar,” the chief justice wrote.

The case was being monitored closely by all sides in the broader immigration debate, where every legal victory or defeat is considered a barometer.

“It’s definitely positive, but I will be cheering when I see Sergio and our other members in California sworn in as lawyers,” said Cesar Vargas, who helped form the Dream Bar Association, a group in similar circumstances as Mr. Garcia.

Mr. Vargas has petitioned to join the New York State Bar Association, while another case involving Jose Godinez-Samperio is pending in Florida.

“This certainly puts pressure on New York because New York has a similar statute that may allow undocumented immigrants to practice law. But Florida doesn’t have anything similar which still highlights that each state can still decide whether to license someone or not,” Mr. Vargas said.

It’s still illegal under federal law for a firm or government agency to hire Mr. Garcia, who does not have federal work authorization. But the justices said they would leave it up to Mr. Garcia to police himself and to be honest with potential clients about what cases he cannot take.

“This court’s granting of a law license to undocumented immigrants would not override or otherwise affect the federal limitations upon the employment of undocumented immigrants,” Chief Justice Cantil-Sakauye wrote. “Nonetheless, for a number of reasons we conclude that existing federal limitations on the employment of undocumented immigrants do not justify excluding undocumented immigrants from admission to the State Bar.”

The Obama administration supports legalization of the nation’s illegal immigrant population and has implemented policies that have allowed millions of illegal immigrants to remain in the U.S. with little danger of deportation.

But the Justice Department has opposed bar admissions for those in the country illegally, arguing in court filings that granting a professional license is a step too far. Department attorneys argued that giving Mr. Garcia a license to practice law was a violation of the federal mandate that no public money be used to grant licenses to people who are in the country without permission.

Being able to apply may not be the end of Mr. Garcia’s fight. Larry DeSha, a California-based lawyer who has fought Mr. Garcia’s application, argued that it would be illegal for an illegal immigrant to enter into a contract with a client, even as an independent lawyer. Mr. DeSha also said giving Mr. Garcia the imprimatur of a license could mislead potential clients.

“The best way to protect the public in this matter is to deny his admission to practice until he becomes legal, can take the oath of office truthfully, can be hired for pay and can enter into legal fee contracts,” Mr. DeSha wrote in a court filing in early December.

Mr. DeSha was still studying the court’s opinion Thursday evening.

Mr. Garcia’s case is different from that of Mr. Vargas or Mr. Godinez-Samperio, the Florida applicant. Both of them were able to get tentative legal status and work permits under Mr. Obama’s non-deportation policy for younger illegal immigrants.

But Mr. Garcia is too old to qualify.

He was first brought to the U.S., illegally, by his parents at 17 months. They lived in California until he was 9, when the family returned to Mexico, then came back to California when he was 17, when he again entered illegally.

His father obtained legal residency, however, and Mr. Garcia is awaiting a visa number for his own legal status.

“He has resided in California continually since that time — for more than 19 years — and has gone to college, completed law school, and has successfully passed the bar examination in California,” Chief Justice Cantil-Sakauye wrote. “He has been a diligent and trusted worker and has made significant contributions to his community. He has never been convicted of a criminal offense.”

The court did say that Mr. Garcia lied to a grocery store where he applied for employment soon after he returned to the U.S., claiming he had legal status. He also was cited for driving without a license, paid the fine, then went to obtain a license from Oregon, which did not check applicants’ immigration status.

But overall, the justices said Mr. Garcia showed “good moral character” and pointed to numerous recommendations from teachers and associates.

Immigrant rights groups praised the decision and said they hoped it was the first bit of good news in a year when they want Congress to pass a broad bill legalizing most illegal immigrants.

“This is a bright new day in California history and bodes well for the future of the United States of America,” said the Coalition for Humane Immigrant Rights of Los Angeles. “We start 2014 with high hopes that soon justice will also be a reality for millions of undocumented immigrant workers who give it their all for the sustenance of their children, the strength of their families, and the vitality of an immigrant nation.”