THE JUDGMENT against Attorney General Janet Reno last weekend was harsh and bipartisan, with Sen. Richard Shelby (R-Ala.), chairman of the Senate Select Committee on Intelligence, openly calling for her resignation and Sen. Robert Torricelli (D-N.J.) all but endorsing this view. The senators were responding to a Justice Department decision in 1997 not to seek a wiretap warrant from the super-secret Foreign Intelligence Surveillance Court to snoop on Wen Ho Lee, the scientist at the center of the current Chinese espionage fervor. Mr. Torricelli said there was "overwhelming evidence that there was probable cause and that national security was being compromised" and that the "failures of judgment by" Ms. Reno were "inexplicable."

We do not know whether the information the FBI brought to the Justice Department's attention concerning Mr. Lee constituted probable cause to believe that Mr. Lee was an "agent of a foreign power." Nobody who has not seen the highly classified proposal squelched by the department can really know. But it is worth remembering before condemning the attorney general that the Foreign Intelligence Surveillance Act (FISA) requires such a finding before surveillance can be authorized, and Ms. Reno on Thursday said that she has reviewed the 1997 decision by department staffers and agrees with their finding that the surveillance application would have been deficient under the law. And a senior Justice Department official told Post reporters Vernon Loeb and Roberto Suro yesterday that no one who reviewed the case thought a warrant or wiretap could be justified. There is, in other words, an irreconcilable conflict between the department's view of this matter and that of Messrs Torricelli and Shelby.

The revelations about lax security in federal scientific facilities described in the Cox report and the sweeping espionage that this apparently permitted are cause for great concern. It certainly seems, moreover, that investigative matters were bungled in the case of Mr. Lee, who was allowed to retain access to classified information and to travel abroad long after he came under suspicion of espionage. But the fact that Mr. Lee was suspected does not necessarily mean that the evidence presented by the FBI would have, if submitted to the FISA court, made up an adequate application. Indeed, there is a real danger in urging the attorney general to err on the side of highly intrusive surveillance that may not meet legal standards.

Part of the central purpose of the FISA, which was passed in 1978 during a surge of post-Watergate reforms, was to prevent unconstitutional surveillance by the executive branch in national security cases. This was to be done by situating the attorney general and the judiciary between the FBI and its wiretapping targets. Ms. Reno -- in addition to being responsible for security matters -- is also responsible for protecting the fundamental rights of Americans.

It is worth noting that the Justice Department under Ms. Reno has used the surveillance powers under FISA quite aggressively, dramatically increasing the number of surveillance warrants sought, and seeking (and getting) from Congress considerable expansions of the court's jurisdiction. The general complaint about the FISA, in fact, is that it is too permissive of surveillance. Whatever problems may exist with the FISA court, one of them is not that the department and the FBI have been generally too timid about using it.

In other words, while the Justice Department's blocking of a FISA application could be a sign of laxity, it could just as easily indicate that it was rightly blocking the illegal surveillance of a man against whom probable cause did not exist and who, to this day, has not been charged with any crime.

If the senators are right and the Justice Department erred, Ms. Reno has a lot of explaining to do, not just for the initial judgment but for her subsequent defense of it. On the other hand, if she is right and the application was deficient, it is a terrible message for Congress to send that the Justice Department should be less vigilant in its review of surveillance proposals. More vigorous security measures and counterintelligence must coexist with vigorous civil liberties protections.