The first year of the Rehnquist Supreme Court is turning out to be, in the words of one chagrined conservative, "Bill Brennan's finest hour."

As the 1986 term draws to a close, with 80 percent of the cases decided -- including the most controversial before the high court this year -- the liberal justices have triumphed in all but two of the blockbuster cases.

The moderate-liberal coalition, led by Justice William J. Brennan Jr., has prevailed in cases on affirmative action, pregnancy leave, discrimination against workers with communicable diseases such as AIDS, asylum for political refugees and the teaching of creationism in public schools.

The conservative wing, supposedly bolstered by the elevation of William H. Rehnquist to chief justice and the addition of Antonin Scalia, has managed to win significant victories only in the area of its traditional strength: criminal law. The court upheld the constitutionality of preventive detention of suspects before trial and rejected a challenge to the death penalty as racially discriminatory. Even in the criminal area, the conservatives lost a case involving the use of victim-impact statements in death-penalty cases.

Liberals and conservatives agree that the first year of the Rehnquist Court has been scarcely different -- perhaps slightly more liberal -- from the preceding 17 years under Chief Justice Warren E. Burger, when a moderate-liberal coalition dominated.

"The major, big cases are done," said Bruce Fein, an attorney with the conservative Heritage Foundation, and Brennan has "marshaled the court in a more skillful way than any chief justice in history."

Justice Lewis F. Powell Jr., the pivotal vote on the court, has continued in that role this term. And, Fein said, "Brennan has gotten Powell's vote on the big ones."

The chief justice, when in the majority, decides who will write the court's opinion in a case. When the chief is in dissent, the most senior justice in the majority assigns the opinion.

"Rehnquist, contrary to some speculation -- including my own -- has not cast a single vote or written a single opinion differently in order to get a majority," Fein said. "Rehnquist has been inept with regard to court politics," he said. "Rehnquist has played his hand so poorly I can't see him pulling together a coalition."

The court this term has issued far fewer splintered opinions, Fein said, and they have been "fairly clear and in general the opinions are shorter."

That means that "Brennan has been able to forge majorities without sacrificing what the decision means. He has been getting five solid votes. That makes the law a little more coherent and stable," Fein said, but not along the lines conservatives would prefer.

Harvard Law School Prof. Laurence H. Tribe, a liberal, agrees with Fein. "It looks more like a Brennan court than a Rehnquist court," Tribe said. "It is quite clear throughout the term that Rehnquist dissented where Burger might have joined the majority to write a narrower opinion.

"That has produced clearer and more enduring victories for liberal constitutional principles in a range of areas than would have otherwise been the case," Tribe said, adding that it has also led to much stronger liberal opinions than if Burger had written the majority opinion or assigned its writing to a centrist justice.

"Those of us who thought the duo" of Rehnquist and Scalia "would be dynamic" and influence the court to the right, "have seen very little evidence of that so far," Tribe said.

There are no cases where the substitution of Scalia for Burger has produced a shift in the outcome to the right, Tribe said, and no sign that Scalia's intellectual prowess has swayed his colleagues.

"He wrote an elaborate dissent in the creationism case that apparently was designed to appeal to someone," Tribe said, but it attracted only Rehnquist's vote.

Scalia joined Brennan in the majority in the pregnancy-leave case but had a different and, Tribe said, better legal rationale. Even so, no one joined Scalia's concurring opinion.

"He doesn't seem to be attracting justices to his corner," Tribe concluded.

One open question last fall after Rehnquist was confirmed was whether he would moderate his views and move toward the center of the court or "continue to be a purist," Tribe said. "Now there is evidence strongly in the direction that he is a principled purist willing to give up influence in order to preserve his integrity. That is an admirable and, for liberals like me, a happy development. It leaves Brennan in charge."

Rehnquist was sharply criticized at his confirmation hearings last summer for the frequency of his lone dissents. He was the lone dissenter only twice last year and twice so far this year. Last year at this time Rehnquist had dissented 28 times and Brennan 33 times. This term, Rehnquist has dissented 28 times and Brennan 36 times.

The key difference is that last year Brennan controlled about 19 opinions all term in cases when he was in the majority and Burger was in dissent. This term he has already assigned about 28 opinions. Brennan wrote only 13 majority opinions last term. So far this term he has written 16.

The liberal victories include:

U.S. v. Paradise, a 5-to-4 decision written by Brennan in February upholding a temporary racial quota for promotion of Alabama state troopers.

California Federal Savings & Loan v. Guerra, a 6-to-3 ruling written by Justice Thurgood Marshall in January upholding the ability of states to require special job protection for pregnant workers.

School Board of Nassau County v. Arline, a 7-to-2 decision by Brennan in March that said federal law forbids discrimination against persons "handicapped" by contagious diseases such as tuberculosis or AIDS.

Johnson v. Santa Clara County, a 6-to-3 decision by Brennan in March that upheld an affirmative action plan in which a woman was promoted ahead of an arguably better-qualified man.

Immigration and Naturalization Service v. Cardoza-Fonseca, a 6-to-3 decision by Justice John Paul Stevens in March making it easier for illegal aliens to receive political asylum.

Booth v. Maryland, a 5-to-4 decision written by Powell last week saying the use of "victim-impact statements in death-penalty sentencing cases impermissibly inflamed the jury.

And, last Friday, Edwards v. Aguillard, a 7-to-2 decision by Brennan striking down a state law requiring that "creation science" be taught whenever evolution is taught in the public schools.