In the Aftermath of Sept. 11

he Justice Department has been relatively restrained in the use of the new terrorism-fighting powers it was granted after the Sept. 11 attacks, but the potential for abuse still exists. That is the message we get from the department's report to Congress this week on how it has employed provisions of the Patriot Act, which greatly expanded the government's authority to investigate potential terrorist threats within the United States.

It appears that several practices that could infringe on civil liberties have not been widespread. The report says that F.B.I. agents from "fewer than 10" field offices visited mosques in their investigations, a new power given to the agency. It puts the number of contacts with libraries in terrorism investigations at about 50, and says that many times a librarian initiated the contact.

The picture on material witnesses is more troubling. The law allows prosecutors to detain potential grand jury witnesses, raising concerns that it could be used to hold people indefinitely without charges. The report states that "fewer than 50" people were held as material witnesses in connection with the Sept. 11 attacks, but it did not dispel reports that as many as half of those held had not ever been called as material witnesses.

On this subject, as on many others in the report, the Justice Department owes Congress a fuller explanation. Though details about investigative targets and detained individuals may not be appropriate for public disclosure, Congress has procedures for keeping such information confidential.

We also remain concerned about the Pentagon's plans for an antiterrorism surveillance system. The program, known as Terrorist Information Awareness — a change from the original, more Orwellian, name, Total Information Awareness — calls for creating a huge computer database to track individuals. It is directed by retired Adm. John Poindexter, whose misjudgments as Ronald Reagan's national security adviser helped produce the Iran-contra affair. The aim is to collect information ranging from financial and medical records to data on the way individuals walk.

It is not clear why the government needs all this information, and what safeguards will be put in place to prevent its misuse. The program's interest in improbable technologies like identifying people by their gait suggests that the entire effort is a gigantic, delusional waste of money.