The man in the unmarked sedan taking pictures at a demonstration is not a tourist. Back at his office, he develops the film, collects snippets about the organization that sponsored the protest, types up the insights of a few "informants" and drops it all in an FBI file stamped "secret."

The scene is not fiction. As it now stands, the FBI can investigate any U.S. citizen on a flimsy suspicion of ties to international terrorism. Agents continue to use that broad authority to scrutinize foreign policy critics and human rights advocates, all in the name of national security.

Rep. Don Edwards (D-Calif.), a former FBI agent himself, wants those invasions of privacy to stop. He believes they threaten Americans' rights to free speech and political dissent. He is pushing for legislation that would require the FBI to have a reasonable suspicion of criminal activity before it is allowed to investigate a U.S. citizen, and he wants the FBI to limit the investigation to gathering evidence on a specific federal crime.

Such measures would have kept the FBI from investigating groups that opposed U.S. policy in Central America in the 1980s. The FBI had to slap its own hand when those investigations were exposed. One probe, into the Committee in Solidarity with the People of El Salvador, or CISPES, resulted in discipline for six FBI agents and a promise from the FBI director that it wouldn't happen again.

Other, less well-known cases, prove that CISPES was the rule, not the exception.

Last summer the FBI reluctantly released a heavily censored, 12-page file on Lois Ahrens of New Hampshire. What had she done to deserve an FBI dossier? She was a peace activist with the American Friends Service Committee, a group that disagreed with U.S. policy in Nicaragua. The FBI released its file on Ahrens, but much of the information was blacked out. It came from a "confidential source who has furnished reliable information in the past."

The Latin American Support Committee of Fresno, Calif., was stunned to find last year that it too had been under the FBI's microscope. What had this group done to deserve an FBI dossier? It had raised money for relief programs in Nicaragua and El Salvador.

The FBI also felt compelled to open a file on Lance Lindbloom of Illinois, because he was quoted in a Chicago Sun Times article as being "very concerned" about the safety of a South Korean dissident.

Edwards' bill would stop those unwarranted investigations and would also keep the FBI from checking on Americans who commit the sin of writing to foreign embassies. One of the FBI's tactics is to record the return addresses on the mail going to certain foreign embassies.

From 1984 to 1989, at least 33 members of Amnesty International were questioned by FBI agents about letters they wrote to the embassies of the Soviet Union and other Eastern bloc countries. These weren't letters of support for the evil empire. They were classic Amnesty International business -- protest letters urging foreign governments to release political prisoners.

If the FBI thought the Amnesty members were in cahoots with the communists, no one paused to wonder why these "spies" used the U.S. mail and put return addresses on their letters. Some Amnesty letter writers were asked if they had "subversive communist" literature in their homes.

Amnesty told us its members continue to be contacted by the FBI regarding protest letters.

The Persian Gulf war has given the FBI a whole new class of people to worry about -- Americans with Arab ancestors. Some 200 of them have received calls from FBI agents wondering if they had any insights into possible terrorist tactics of Iraq. That's akin to calling all Americans named O'Reilly and asking them if they know what the Irish Republican Army is up to these days.

The FBI has come a long way since J. Edgar Hoover was Big Brother, but the tendency is still to consider every American a potential file. One veteran agent told our associate Jim Lynch that he thought the bureau had toned down its domestic spying. But he added that plenty goes on in the agency that most agents don't know about.

He also told us that the bureau keeps secret files on its own people and bugged one agent's bedroom looking for evidence of hanky-panky.

You can expect the FBI and Attorney General Richard Thornburgh to call Edwards' bill an infringement of the FBI's mission. FBI Director William Sessions was candid enough to admit that the guidelines are unclear on investigating U.S. citizens when terrorism is the issue. The Justice Department issued a revised set of guidelines, some of which are classified, of course.