The Justice Department, fearful of the future security of the nation, has accused a three-judge panel of the District of Columbia Circuit Court of Appeals of having imposed "stringent new constitutional standards" on government inquiries into "the loyalty and suitability of its employees."

The court has indeed placed a new burden on government loyalty sleuths. Still to be determined is whether that panel will be upheld in its decision that government workers in nonsensitive jobs are protected by their right to freedom of association from being subjected to a routine FBI full field investigation on the basis of mere suspicion of disloyalty. This is the first court to brandish the First Amendment in this way, and the Justice Department has urgently petitioned for a rehearing by the full Court of Appeals.

The case is that of Harry Kenneth Clark, who, from 1973 to 1979, was a reshelver of books at the Library of Congress. He had no access to classified material and had an excellent work record. Having attended several meetings of the Young Socialist Alliance, which is affiliated with the Socialist Workers Party, Clark was put on the YSA mailing list. Both groups are lawful political parties. They do not advocate violence. The only danger they pose is that, in view of the incessant volubility of many of their members, an undercover agent may some day be talked to death.

Since informers, like the poor, are always with us, the FBI was told in 1975 about Harry Clark's hobnobbing with the Young Socialist Alliance. The FBI informed the Civil Service Commission, which told the Personnel Security Office of the Library of Congress. In 1976, the Library of Congress requested the FBI to conduct a "full field investigation" into Clark's political beliefs and activities while also picking up anything else that might "reflect adversely on his suitability for continued federal employment."

With their customary cool solemnity, FBI agents went calling on Clark's co- workers. They asked not only about his political beliefs but also about what he did on vacations. And was he a homosexual? Former teachers and neighbors of this person under suspicion were also interviewed as well as Clark's parents, siblings and grandmother. The bureau diligently checked his school and college records. The investigation was so thorough that an agent tracked down Clark's junior high librarian and had a nice chat with her.

Clark's record turned out to be absolutely clean. But the process of being "cleared" turned his life upside down. Friends and family advised him to cease his political activities, and he testified at trial that he has indeed become "chilled" in the exercise of his First Amendment rights because of all this attention paid to his political beliefs by the government. Clark has also contended that having his privacy so massively invaded has been rather traumatic. Another claim is that, despite his excellent record, he was continually denied promotion from 1977 to 1979, when he left the Library of Congress. The FBI had exculpated him, but, he feels, his employers still viewed him with some suspicion. After all, he had been investigated by the FBI, hadn't he?

The District Court held that the Library of Congress had a right to ask the FBI to probe Clark's suitability, political and otherwise, for employment. On appeal, however, Judge Edmund Palmieri, speaking for Chief Judge Spottswood Robinson, Judge Patricia Wald and himself, noted that "(l)ike other citizens, government employees . . . have a constitutional right to form political beliefs and lawful associations without government intrusion." The government cannot ustify impairing that right "on a showing of mere legitimate state interest."

If the government wants to unleash the FBI on a future Harry Kenneth Clark, Judge Palmieri concluded, it will have to show that "the investigation was necessary to serve a vital governmental interest and that the full field investigation was the means least restrictive of Clark's First Amendment rights." But, the appeals court declared, in this case, the ubiquitous prying into a reshelver's private life and political views hardly served a vital government interest. Accordingly, the full field investigation was constitutionally out of line.

To justify what the Library of Congress had asked for, and the FBI had implemented, "would be to sanction intrusive and injurious investigations initiated on the basis of minimal information regarding an employee's association with a lawful political group, no matter how menial or inconsequential the position of the employee might be."

But the Justice Department insists the sky will fall if the government is impeded by this court's having imposed "constitutional limits on the initiation and conduct of such investigations."

I expect that government lawyers in the regimes of Eastern Europe, empathizing with their counterparts here, may be following this case with considerable interest.