Of the 2.1 million jobs in the federal government, John W. Mendenhall figures he had one of the best. For most of his 35 years in the bureaucracy, Mendenhall was paid, basically, to watch movies.

Not just any movies, but supposedly educational ones, along with reviewing educational film strips, recordings, maps, charts and models. And lots of films, perhaps 90,000 in all, while he worked for the U.S. Information Agency.

Until his retirement Jan. 2, Mendenhall, a Kansas City native and "as American as you can get," was chief attestation officer of the United States.

His was a little-known office that was empowered to determine whether U.S.-made films should be certified for duty-free export status, a power that was tantamount to life or death for many small, independent film makers.

Mendenhall, who worked in the office for almost 30 years and headed it for the past eight years, viewed himself as "a facilitator," helping educational institutions around the world gain access to the thousands of films produced by America's $1 billion-a-year educational film industry.

But last year some film makers and a federal judge in California decided that Mendenhall had been something else.

They said he was a government censor, wielding a broad and unconstitutional power to determine which films were "educational" and which were "propaganda."

"This is an insidious form of censorship, allowing government officials to make decisions about what others are to think," said the Pen American Center, a New York group that includes Norman Mailer, John Irving, Kurt Vonnegut, Robert Caro and other well-known writers.

"Not only is our business at risk," complained Donald Barr, president of Barr Films of Pasadena, Calif., "but USIA is unilaterally affecting the free flow of audio-visual material throughout the world."

To the dismay of many film makers, the U.S. Information Agency's reaction to the Oct. 24, 1986, ruling by U.S. District Judge A. Wallace Tashima was effectively to shut down Mendenhall's office, declaring it could not continue to review anything without regulations.

The Los Angeles judge had stunned government lawyers by declaring three key sections of the film regulations unconstitutional. They included a verbatim section of a 1948 Beirut agreement establishng the protocol under which 72 nations now exchange educational and scientific audio-visual materials without import duties.

The issue was raised by six film makers who complained in court papers that they had been denied approvals because their films were critical of the Reagan administration or government policies.

Tashima said he didn't have to consider their individual complaints because USIA's regulations were clearly unconstitutional. " . . . The agency's treaty obligations to certify what's 'educational' may not, consistent with the Constitution, place USIA in the position of censor," the judge wrote.

He ordered the agency to "promptly" reconsider six films it had rejected. The agency appealed, insisting that "censorship is not at issue here."

The issue, the Justice Department has told the 9th U.S. Circuit Court of Appeals, is only whether a film is recommended by the USIA for duty-free status. Any film denied a USIA certificate still may be sent overseas, the lawyers have said.

Last month, faced with USIA's announcement that it could not review films without new regulations, Tashima accused the agency of "foot-dragging" and directed it either to publish new regulations by Nov. 16 or declare that it will issue future certificates without regulations.

The impasse has created a huge backlog of unscreened films and other audio-visual materials at USIA's screening office on D Street Southwest.

As of last week, the agency had returned 3,163 audio-visual items submitted to it, including 932 movies, according to USIA spokeswoman Jane Taylor. "We cannot consider any materials if we have no regulations," she said.

Mendenhall, 63, who retired to Alexandria this year saying he was ready for a change, said he rejects the idea that he acted as a censor. "Nonsense, I just categorically deny this," he said.

What his office attempted to do, he said, was to judge each film on its merits. "We have to ask: Is this a full and fair treatment of the subject? Or is it slanted to a point of view?"

If the film is found to be biased, inaccurate, commercial or an entertainment film, it has to be rejected under the agency's rules, he said.

"If we got in the business of having to certify all films, we would have to do it for the Ku Klux Klan and any fringe group that comes down the pike," he said. If the program becomes filled with such films, he said, foreign governments will become skeptical of accepting all U.S. films and the program's value will be debased.

Civil-liberties lawyers, who brought the suit on behalf of six films denied approval by Mendenhall, reject his fears as exaggerated. Typically, fewer than 20 films a year are rejected, according to Mendenhall's own count.

Mendenhall said that he and his staff of six often approved films sight unseen, depending on a written description of the film and the reputation of the film company to produce an unbiased, accurate film, clearly aimed at an educational audience.

The requirements come from Article I, Section (a) of the Beirut agreement, which Mendenhall can cite by heart: "Visual and auditory materials shall be deemed to be of an educational, scientific and cultural character when their primary purpose or effect is to instruct or inform."

Judge Tashima said that that was the problem. The government has no power under the First or Fifth amendments to determine what is accurate.

"There is an inherent structural problem in the regulations," said David Cole, a lawyer for the Center for Constitutional Rights, the nonprofit New York-based group that brought the lawsuit.

The suit grew out of the frustrations of producers of an award-winning documentary about uranium-mining dangers, "In Our Own Backyard." Denied a duty-free recommendation by USIA, the TV producers came to the center, furious that USIA had rejected their film partly on the advice of the Energy Department, which was criticized in the film, Cole said.

Cole's group and the American Civil Liberties Union have urged USIA to draft new regulations that prohibit the agency from rejecting films on the grounds that they express a point of view, espouse a cause, are considered unbalanced or are critical of the United States.

In any event, both Cole and the judge have suggested that USIA may not need regulations. Of the 72 nations under the agreement, only the United States and Canada have screening regulations.

The goal of the Beirut agreement was "the uninhibited exchange of ideas," Cole said. To shut the reviewing process, effectively ending U.S. participation in the Beruit agreement, puts USIA in an "inherently hypocritical position," he said.

Perhaps not. Mendenhall recalled this week that when he was first recruited to the office in the 1950s, he and one of his predecessors often said that they hoped an unfettered exchange of audio-visual materials would be accepted by all nations.

"It was always our hope that we could go out of business one day," he said.