SANTA ANA, Calif. — A federal judge decided yesterday that a reporter who used confidential sources in a story on export-conspiracy indictments would not have to reveal those sources to him, but it became public during the hearing that the journalist would be called to appear before a grand jury seeking the same information.

U.S. District Judge Cormac J. Carney said that although he thought someone violated a rule barring federal officials from giving information about grand jury proceedings to outsiders, he believed Washington Times reporter Bill Gertz was performing a crucial public service in his reporting.

"I think it's a very newsworthy case," Carney said of Gertz's reporting on an indictment of Chi Mak, a Chinese-born engineer who is now serving a 24-year sentence in federal prison. "The freedom of the press is a paramount interest."

Mak, who worked for a defense contractor, was convicted last year of conspiring to export U.S. defense technology to China, among other charges. Four of his relatives made plea deals in the case.

Gertz cited U.S. government sources in a 2006 story that said an indictment of Mak had been approved and four relatives also would be indicted.

Mak's attorneys objected to the story, contending the government violated the rule prohibiting the leak of information revealed during grand jury proceedings. Carney ordered an investigation to determine who leaked the information and subpoenaed Gertz.

Gertz, who reports on national security, briefly took the stand and was asked by Carney whether he would voluntarily reveal his confidential sources.

"No, sir," Gertz responded. When Carney asked questions about newsworthiness and the importance of keeping sources confidential, Gertz repeatedly read from a prepared statement that invoked his Fifth Amendment right against self-incrimination.

Gertz read from the same statement when questioned by Stanley I. Greenberg, an attorney for one of the defendants in the conspiracy case.

Greenberg said Gertz should not be able to invoke his Fifth Amendment rights after submitting a declaration earlier this week that stated his reasoning for not revealing his sources.

The judge disagreed, saying that because of a government letter advising that Gertz would be subpoenaed by a grand jury investigating the leak, he could invoke his right to not testify in yesterday's hearing.

Gertz's attorney, Charles Leeper, said afterward that Gertz had yet to receive a grand jury subpoena.

"Confidential sources are the lifeblood of a free press, independent of government control," Gertz said outside after the hearing. "The identity of these confidential news sources must be protected if our press freedoms, fundamental to the effective functioning of our democratic system, are to endure."

Carney's decision comes at a time when legal protection for reporters who use confidential sources is being debated on Capitol Hill.

On July 22, Senate Majority Leader Harry Reid, D-Nev., announced that the Senate would consider the Free Flow of Information Act, which would provide a federal privilege for reporters. The House approved a similar measure in October.