The U.S. Court of Appeals here ruled yesterday that journalists, historians, political scientists and others have a right to try to win the release of former president Nixon's presidential papers and tape recordings by filing Freedom of Information suits.

Lawyers for Nixon had contended that the Presidential Recordings and Materials Act dictates that only the General Services Administration could set the terms for realse of any of the 42 million documents and tape recordings that Nixon accumulated in his 5 1/2-year presidency and that no Freedom of Information suits could be filed to gain release of the material.

But the appellate court unanimously ruled that Congress clearly intended the public to have the right to file the suits to see the Nixon documents.

In issuing the ruling, the appeals court reversed a decision by U.S. District Court Judge Aubrey E. Robinson Jr. who had dismissed suits brought by the Reporters Committee for Freedom of the Press and others to win access to the Nxion documents through Freedom of Information suits and a declaration that the government, not Nixon, owns the materials. He ruled that the questions were moot because of passage of the Recordings and Materials Act.

Robinson ruled that the Freedom of Information suits could at least not be used to gain access to the documents until GSA has finished sifting through and classifying the documents-and possibly not at all.

But the appeals court, in a decision written by Judge Edward A. Tamm and concurred in by Judges J. Skelly Wright and J. Edward Lumbard, said that the ownership question was not resolved by passage of the Recordings and Materials Act nor decided in another Nixon court case concerning the papers.

GSA archivists are currently sorting the documents into three classifications: material that is personal to Nixon and should be returned to him, material that should be retained by the government and made public and material that should be retained by the government and not made public.

Meanwhile, Nixon has brought another suit objecting to the procedures being used in sifting the papers and the definitions as to how the documents should be classified.