SAN FRANCISCO — A federal judge yesterday refused to dismiss a lawsuit challenging the Bush administration’s wiretapping program, rejecting government claims that allowing the case to go forward could expose state secrets and jeopardize the war on terror.

U.S. District Judge Vaughn Walker said the warrantless eavesdropping has been so widely reported that there appears to be no danger of spilling secrets.

Dozens of lawsuits alleging that telecommunications companies and the government are illegally intercepting Americans’ communications without warrants have been filed. This is the first time a judge has ruled on the government’s claim of a “state secrets privilege.”

“It might appear that none of the subject matter in this litigation could be considered a secret given that the alleged surveillance programs have been so widely reported in the media,” Judge Walker said.

Judge Walker also wrote that he did not see how allowing the lawsuit to continue could threaten national security.

“The compromise between liberty and security remains a difficult one,” Judge Walker said. “But dismissing this case at the outset would sacrifice liberty for no apparent enhancement of security.”

And in declining to dismiss AT&T Inc. from the lawsuit, filed by the Electronic Frontier Foundation privacy group, Judge Walker suggested the case had some merit. “AT&T cannot seriously contend that a reasonable entity in its position could have believed that the alleged domestic dragnet was legal,” he wrote.

A Justice Department spokesman said the administration was reviewing the ruling before making its next step.

The lawsuit challenges President Bush’s assertion that he can use his wartime powers to eavesdrop on Americans without a warrant. It accuses AT&T of illegally cooperating with the National Security Agency to make communications on AT&T networks available to the spy agency without warrants.

The government intervened in the case, telling Judge Walker that Mr. Bush’s surveillance program, adopted after the terror attacks of September 11, 2001, attacks, is “a secret of the highest order.”

The government argued that divulging any information about any alleged collusion between AT&T and the government to eavesdrop on Americans could subject AT&T employees and facilities to attack and would enable terrorists “to communicate more securely.”

The state secrets defense, first recognized by the U.S. Supreme Court in a McCarthy-era lawsuit, has been increasingly and successfully invoked by federal lawyers seeking to shield the government from court scrutiny.

The high court has upheld the legal tactic as recently as January, when it rejected an appeal from a former covert CIA officer who accused the agency of racial discrimination.

The president confirmed in December that the NSA has been conducting warrantless surveillance of calls and emails thought to involve Al Qaeda terrorists if at least one of the parties to the communication is outside America.

The administration contends the program is legal and necessary, but has been mum on whether purely domestic calls and electronic communications are being monitored, as the lawsuit alleges.