A judge's decision today on Inslaw Inc.'s allegations that Justice Department officials tried to drive it out of business may turn on how he views the circumstances under which a key figure in the alleged vendetta left the company.

The Washington software company says the former official, C. Madison Brewer, was fired, and thus was biased against it when he became responsible for administering a contract with the company for the Justice Department.

But in recent weeks, Justice Department lawyers have begun to argue that Brewer left Inslaw amicably and on his own, and even was given a going-away party.

The differing versions of Brewer's departure may be a key factor when a federal bankruptcy judge, George F. Bason Jr., announces his decision today in the two-year-old lawsuit, in which Inslaw alleges that Brewer and other Justice officials carried out a vendetta against the company.

The Justice Department, however, says the case is little more than a standard contract dispute between the department and a company that failed to deliver software to automate U.S. attorneys' offices.

Bason has ruled previously that the Justice Department improperly attempted to force Inslaw, which filed under Chapter 11 of the federal bankruptcy code in February 1985, to liquidate under Chapter 7 of the bankruptcy code.

Most of the arguments made in recent exchanges of briefs in the case repeat previous contentions about Inslaw's compliance or noncompliance with the Justice Department contract, whose cancellation forced the company into bankruptcy.

But until the case went to a week-long trial this summer, the Justice Department had not disputed Inslaw's version of why Brewer left the company in 1976 to join the Justice Department, where he eventually wound up overseeing Inslaw's contract.

Testimony at the trial raised the possibility that Brewer had resigned his post as the company's general counsel, although perhaps under pressure. The department has argued in briefs filed since the trial that possibility seriously undermines Inslaw's contention that Brewer was biased against the company and its chairman, William A. Hamilton, because he had been terminated -- a cornerstone of the company's case.

"I have always thought I left because I did not fit in, that I did not feel comfortable or professionally rewarded being there," Brewer testified in July. "I caused the departure." The Justice Department says internal Inslaw documents and other evidence also do not show that Brewer was fired.

"Mr. Hamilton never told Mr. Brewer he was being 'fired,' " the Justice Department said in a filing earlier this month. "Both men considered the parting to be amicable. ... Mr. Brewer retained business and social contacts with {Inslaw}.

"Inslaw's contention that Mr. Brewer was fired by Mr. Hamilton is irrelevant," the department said. "Mr. Brewer could only be biased against Inslaw and Mr. Hamilton if Mr. Brewer believed he had been fired, whatever Mr. Hamilton's belief, and Mr. Brewer did not, and does not, believe he was fired."

Not surprisingly, Inslaw has taken issue with the Justice Department's version. The company says Hamilton decided that Brewer's work "was unsatisfactory and that he would have to make efforts to improve or consider leaving his employment."

Later, Inslaw contends, Hamilton repeatedly asked Brewer to look for another job, and then terminated him.

"While Mr. Hamilton did not use the word 'fired,' there could be little doubt as to the fact that Mr. Brewer was asked to resign," the company said in a brief filed with the court last week. "While the parting was amicable, Mr. Brewer nevertheless held strong negative feelings about Mr. Hamilton and Inslaw."

Indeed, Inslaw says, Brewer made repeated negative statements about Hamilton and Inslaw after he left the company.

At the trial, Brewer testified that he believed Hamilton had a messianic personality and a distorted view of reality, and admitted that he once told a prospective Inslaw employe that Hamilton could be an "M.O." -- shorthand for someone who should be sent away for "mental observation."

But Brewer said he did not let his opinions of Hamilton interfere with the Justice Department-Inslaw relationship. "I did not view our problems as being personality problems or personal problems," Brewer testified.

"Whatever feelings Mr. Brewer may have had regarding Inslaw and/or Mr. Hamilton, those feelings never led Mr. Brewer to commit any affirmative act to Inslaw's detriment, or to induce other DOJ employes to take any such action," the Justice Department said. "Even if Mr. Brewer was biased against Inslaw, which he was not, that bias had no impact on the administration of the contract."

But in its brief earlier this month, Inslaw said, "Given the extraordinary admissions made by Mr. Brewer himself about his bias against Mr. Hamilton, the assertion that he could not be biased unless he was 'fired' is absurd.