A federal judge here has ruled that a Wall Street Journal reporter does not have to divulge the names of confidential sources he used for two 1979 stories that two Justice Department prosecutors claim defamed them.

U.S. District Court Judge Harold H. Greene said in a 19-page opinion Wednesday that, for various reasons, the reporter, Jim Drinkhall, does not have to reveal the names of the 10 sources, but left open the possibility that disclosure of three of the names might be warranted at a later date.

In an April, 1979, article, Drinkhall wrote of an alleged plan by William M. Kramer, a San Francisco-based member of the Justice Department's organized crime strike force, "to pressure a federal prisoner Sam Ray Calabrese into providing evidence to the government about a supposed 'underworld' associate," Greene said.

In addition, the article attributed to John D. Dowd, then a strike force attorney based in Washington and now a private attorney here, other statements about Calabrese's usefulness as a government informer.

In the second article, in December, 1979, Drinkhall wrote of the aftermath of the first story, recounting how journalistic colleagues "were asked for derogatory information about him and how a rumor was circulated that he had written the first article because he was on the payroll of organized crime," Greene said.

The judge said "it appears to the court that Kramer and Dowd have made at least a threshhold showing that Drinkhall did indeed fabricate the existence of some sources or misrepresent the evidence they would be likely to provide."

Drinkhall says that his sources do exist, but has refused to divulge their names because he had promised not to reveal their identities.

The judge said that, in the case of two sources for the first article, "the First Amendment interest in protecting" their identities "far outweighs" Kramer and Dowd's need for their testimony.

In the case of four other sources, Greene ruled that their testimony likely would bear more on Drinkhall's credibility than on the validity of the story. The judge said that, as a result, their possible testimony would add little of substance to evidence that Kramer and Dowd have already collected in the case.

But Greene also ruled that when the case goes to trial Drinkhall cannot use any unidentified source "as evidence of truth or lack of malice."

Greene said that the identity of a seventh source "is not crucial" to the case and that disclosure of the names of three strike force attorneys used by Drinkhall as sources for the second story might be "of substantial importance", but that it was premature to make a decision now.