The Central Intelligence Agency does not have the authority to investigate an American citizen if is considering hiring without informing that person, the U.S. Court of Appeals ruled here yesterday.

The ruling, believed to be the first of its kind, came in a Freedom of Information suit filed by a Washington resident who is seeking files the CIA maintains on him.

Gary A. Weissman wrote the CIA in 1975 after reading news stories concerning CIA investigations of political activists. He said he had been active in politics in the 1960s and asked to "see all files completed on me by the CIA."

As a result of partial disclosures by the CIA, Weissman found out that he had been considered for CIA employment during his college days in the late 1950s and early 1960s, although the agency never informed him or offered him work.

The CIA refused to turn over all of its files to him, however, saying the records were exempt from disclosure under the FOIA because they were "compiled for law enforcement purposes." A lower court her upheld that CIA claim.

U.S. District Judge Gerhard A. Gesell, sitting as an appellate judge in this case, rejected the CIA argument. Agreeing with Judge Gesell were U.S. Circuit Judges Carl McGowan and Edward A. Tamm.

Although the CIA investigation of Weissman may have been a "genuine attempt" to determine if he could be hired by the CIA, the agency does not have the authority to conduct an "extensive investigation over a five-year period of an American citizen living at home, without his knowledge," Gesell said.

He pointed out that Congress had sought since the agency's inception "to make sure that when it released the CIA genie from the lamp, the Agency would be prevented from using its enormous resources and broad delegation of power to place United States citizens living at home under surveillance and scrutiny."

"A full background check within the United Sates of a citizen who never had any relationship with the CIA is not authorized, and the law enforcement exemption is accordingly unavailable," Gesell wrote.

The appeals court did not order the material immediately turned over to Weissman, but instead instructed the lower court judge to consider other objections the CIA might have to releasing the material.