DOCUMENTS OBTAINED as a result of a Freedom of Information lawsuit and released this week show a picture of intense investigation by the FBI of an organization dedicated to opposing the administration's policies in Central America. The Committee in Solidarity With the People of El Salvador (CISPES) was the subject of probes in 1981-82 and 1983-85. The nationwide investigation included surveillance of members, use of undercover agents and the accumulation of files that included photographs and other personal data on those who had attended organization meetings or public demonstrations. In connection with this inquiry, the FBI also looked into politically active organizations as diverse as the Maryknoll Sisters and the United Auto Workers. It was a wide-ranging and intrusive investigation, and it produced not a single charge of wrongdoing.

Members of CISPES charge that the entire effort was politically motivated and designed to intimidate those who oppose administration policies abroad. The FBI cites national security in refusing to discuss the case in detail, but does claim that its investigations were based on "alleged criminal activity" by group members. But if that activity included allegations of terrorism or national security breaches involving a foreign power, different FBI guidelines apply to initiating an investigation, and those guidelines are secret. Current law also provides that certain investigative techniques such as breaking and entering and searching without warrants can be undertaken if the attorney general finds that the target of an investigation is an agent of a foreign power. No one knows whether that special power was invoked here, but CISPES members believe it was.

Last summer, the House Judiciary Committee and both the House and Senate intelligence committees looked into charges that the FBI investigation of CISPES was a case of egregious harassment of legitimate political opponents of U.S. policy. Nothing came of these inquiries, but with the release of 1,200 documents detailing the extent of the FBI investigation and raising questions about its justification, it is time for a new look by Congress.

The House Judiciary Committee is expected to question Director William Sessions about the case in March, but he will probably refuse to give public testimony in that forum. The intelligence committees should ask him to explain and defend this massive effort and to demonstrate, if he can, that this was not a case of political harassment. The committees also ought to consider legislation to set standards for counterintelligence and terrorism investigations and assume an oversight responsibility for these cases. As it is now, the potential for violating the civil liberties of political dissidents under the guise of national security is too great.