A federal judge ruled today that patriotism was irrelevant to the espionage trial of former Navy intelligence analyst Samuel Loring Morison and refused to permit any evidence bearing on it.

The decision stunned Morison's attorneys, who had been planning to depict him as a loyal American and stout believer in a strong Navy who would never have intentionally weakened the nation's defenses.

U.S. District Judge Joseph H. Young held, however, that the espionage laws under which Morison is being tried hinge on cut-and-dried factual questions about what Morison did, no matter how laudable his motives.

The ruling came this evening as government prosecutors prepared to wind up their case against Morison on charges of leaking three secret KH-11 spy satellite photos in August 1984 to a British magazine and keeping portions of two other classified documents at home in his Maryland apartment.

Morison admitted sending the photos to Jane's Defence Weekly in a statement he gave to Naval Investigative Service and FBI agents on the night he was arrested, Oct. 1, 1984.

The two other documents, concerning a series of devastating explosions at a Soviet Navy ammunition depot earlier that year, were seized in a search of his apartment that same evening. Examination of the typewriter ribbon Morison used at the Naval Investigative Support Center showed that he had typed a summary about the fire in the summer of 1984 and sent that off to Jane's as well.

Faced with those facts and more, defense lawyers Robert Muse and Mark Lynch have been arguing that Morison sought no payments for his submissions to Jane's, but was instead bent on alerting the public to the growing threat posed by the Soviet Navy. In videotaped depositions taken at the Justice Department late last month, for instance, two London-based executives from Jane's, which Morison had served since 1976 as a contributing yearbook editor, testified that he was "a very patriotic" American.

The question of whether the jury would be allowed to hear those remarks first came up on Wednesday. Chief prosecutor Michael Schatzow objected to any mention of Morison's loyalty, saying that "motive is not an element in this case."

Judge Young said he agreed, but said he would reconsider if the defense could muster fresh arguments. He has held that all the government needs to do is show that Morison "willfully" transmitted photos and documents "relating to the national defense" to someone "not entitled to receive" them.

"Comments about [Morison's] patriotism and similar characteristics," he said, "will not be admitted."

Partly for that reason, the videotapes of Jane's Defence Weekly Editor-in-Chief Derek Wood and Jane's Publishing Co. Ltd. Managing Director Sydney Jackson were carefully censored when they were played today.

Testifying under a grant of immunity from criminal prosecution, both the editor and the publisher said it was Morison who sent the magazine details about the ammunition depot fires -- which were then incorporated into an "exclusive report by Derek Wood" for the July 14, 1984, edition. They said they "assumed" Morison was the source of the spy satellite photos, but these were actually mailed by their Washington advertising representative, Anne McKrill. Jackson said he returned the photos, one of which turned out to have Morison's thumbprint on it, to a representative of British intelligence in the aftermath of their publication.

Prosecutor Schatzow said the witnesses from Jane's insisted on immunity in return for coming to the United States to testify. He said they also insisted on giving depositions instead of appearing at trial. They could not have been subpoenaed.

Defense attorney Muse sought permission for a limited patriotism defense at day's end, asking the judge to permit asking future witnesses questions such as: "Do you have an opinion whether Mr. Morison would knowingly harm the United States?"

Judge Young replied, "I don't think they're relevant" and said he would issue a written order to that effect.