U.S. Court of Appeals Chief Judge Spottswood W. Robinson III, in an opinion that could have significant implications for newspaper columnists and other commentators, wrote yesterday that statements published as opinion but suggesting specific facts can be considered libelous if they omit data supporting another point of view.

His opinion, which grappled with a nebulous area of libel law involving the difference between fact and opinion, came in a unanimous decision by a three-judge appeals panel to reverse a lower court ruling in the case of a University of Maryland professor who claimed he was defamed in a 1978 newspaper column by syndicated writers Rowland Evans and Robert Novak.

The case now goes back to the lower court for a rehearing. Judges Patricia M. Wald and George E. MacKinnon agreed the case should be reheard. But Wald, who called Robinson's opinion "intriguing," voiced concerns over how the test would be applied. MacKinnon said he considered the column "opinion" and that the general reading public also would view it as such.

The professor, Bertell Ollman, claimed Evans and Novak libeled him when they asserted that his mission in the university classroom was to convert students to Marxism and that he was held in low esteem by colleagues. A U.S. District Court judge had dismissed the suit on the grounds that the columnists' assertions were opinions and therefore protected under the First Amendment.

Robinson wrote that Evans and Novak had offered their conclusions not as "pure opinions" but as statements with a factual basis. The columnists failed to give a complete factual representation, he stated, and therefore may have libeled Ollman.

Published expressions of opinion have in general been protected from libel suits, while statements of fact carry no such privilege. But a precise definition of what is "fact" and what is "opinion" has consistently eluded the courts.

Robinson, noting that the Supreme Court has been "virtually silent" on what, exactly, constitutes opinion, attempted to establish a specific category of statements that can lose the First Amendment protection because of factual deficiencies.

Robinson called such statements "hybrids," which he wrote "differ from pure opinion in that they are remarks which most people would regard as capable of denomination as 'true' or 'false,' depending upon what the background facts are revealed to be."

A "hybrid" can become libelous, Robinson wrote, when it "appears without any recitation of the underlying facts, or when those facts are stated erroneously or incompletely."

A spokesman for Evans and Novak referred a reporter's queries to the columnists' attorneys in Chicago, who could not be reached for comment yesterday.

Ollman also could not be reached.

Ollman claimed in his suit that because of the column, he was denied the chairmanship of the university's political science department, a position for which he had already been approved by the university provost and chancellor of the College Park campus.

One of the disputed portions of the column asserted that Ollman was viewed by colleagues as a "political activist." That term, as used in the column, Robinson wrote, "reasonably could be viewed as the antithesis of scholarship." He said the statement might in one context be viewed as "pure opinion," but as used in the column implied "the existence of facts . . . and there is little sign of any such factual predicate in the column."

A survey offered in the case by Ollman, which showed him ranking 10th highest in prestige among 317 of the nation's leading political scientists, "raises a genuine issue as to whether there was a culpable omission or error in the background facts presented to the reader," Robinson wrote.

As examples of Ollman's alleged intent to recruit students as communists, Evans and Novak also had exerpted quotes from an article Ollman had written. The lower court had found that portions of Ollman's article "contrary to Evans' and Novak's viewpoint are carefully omitted."

Robinson wrote that the use of the excerpted passages in the column "present a genuine issue whether the absolute privilege for opinion has been forfeited by culpable omissions or errors in the supporting facts which the article offered its readers."