A FEDERAL COURT recently ruled against Abdeen Jabara, an American lawyer who had sued the government for secretly tapping his phone for years. The decision raises serious questions about government adherence to Fourth Amendment restrictions on unreasonable search and seizure. More importantly, it highlights long-standing questions about the nature and actions of the National Security Agency (NSA).

A branch of the Department of Defense, the NSA has the primary task of monitoring the communications of foreign governments and protecting the electronic communications of the United States. Thousands of listening posts worldwide and a vast computer complex in Maryland allow the NSA to tap into and record all electronic messages entering or leaving the country. A 1975 post-Watergate Senate panel described the NSA setup as a "giant vacuum cleaner." But unlike domestic law-enforcement agencies, which must obtain a warrant from a Federal Judge before tapping phone messages, the NSA gets warrants from a special secret panel of judges.

There are several problems with the NSA's structure. By shrouding the warrant process in secrecy, the government restricts the public from finding out or reviewing when and why wiretapping is authorized. The use of secret judges also distorts the warrant-requirement limits placed on domestic law-enforcement agencies. In the Jabara case, for example, the NSA supplied tapped information to the FBI, 17 domestic agencies and three foreign governments. The FBI, which never formally charged the lawyer with any crime, could not have obtained a warrant on its own.

The NSA was founded by President Truman in 1952, under the terms of a memo whose contents are still classified and inaccessible, even to Congress. No law has ever defined the permissible scope of activities of the NSA, yet its budget and staff are many times larger than any other American intelligence organization. Undoubtedly, the demands of national security require the surveillance of possible foreign agents. But the NSA remains unduly immune to public or Congressional oversight.

The dangerous potential of the NSA is obvious from incidents like the Jabara case. Congress should open an investigation of the NSA and its operations, especially the secret warrant process. If our government plans to expand its ability to keep track of its own citizens, the matter should at least be brought out into the open.