THE SUPREME COURT opens its 1988-89 term Monday with cases dealing with affirmative action, drug testing and the death penalty - issues that will not only reveal the direction of its newest member, Justice Anthony Kennedy but of the court itself.The court has appeared ready to tip to the right ever since Chief Justice William Rehnquist ascended to the center seat on the court of nine, but the lack of a consistent fifth conservative vote kept the court teetering back and forth, liberal on most social issues and conservative on criminal law.

Kennedy, President Reagan's third and ultimately successful replacement for centrist Justice Lewis Powell, could be that fifth vote despite attempts during his nomination to portray him as another Powell.

That belief has not been lost on at least one member of the court. Justice Harry Blackmun told law students at the University of Arkansas at Little Rock that he thought it a "distinct possibility" that the Roe vs. Wade decision that legalized abortion could "go down the drain" this term.

Blackmun, who has cried wolf over the fate of his most famous decision before, also said the court could be changing direction, depending on how far to the right Kennedy moved.

Court watchers and legal scholars agree that this term is pivotal.

John Powell, legal director of the American Civil Liberties Union, said, "If last term's decisions are any indicator, Justice Kennedy may favor government prerogatives over individual liberties more consistently than did Justice Powell."

"I think it's probably predicting too much" to say this is the year the conservative majority will emerge, said A.E. Dick Howard, a former Supreme Court law clerk and professor at the University of Virginia Law School. ". . . We will have the evidence, but it will take more than one term to nail down the trend."

Of course, whatever direction the court takes could be radically altered by the election. The next president will likely be called on to replace one or all of the members of the liberal wing of the court - Justices William Brennan, 82, Thurgood Marshall, 80, and Blackmun, who will be 80 in November.

Howard said that unlike last term, when most of the controversial cases were disposed of before the arrival of Kennedy, this term has a docket full of cases that invite ideological distinctions.

The top cases before the court include:

-Whether a landmark 1976 civil rights ruling protecting blacks from discrimination by private businesses and schools should be overruled. The court will consider overturning Runyon vs. McCrary in a case brought by a black woman charging her employer with racial harassment.

-The constitutionality of affirmative action laws requiring a percentage of government contracts to be awarded to minority businesses. The case involves an ordinance in Richmond, Va., requiring contractors on city construction projects to subcontract at least 30 percent of the work to companies owned by minorities.

-The constitutionality of drug testing. The court will tackle the issue in two cases, one testing a Customs Service regulation requiring drug tests of all new applicants and employees seeking promotions to so-called sensitive positions and the other a government rule requiring drug tests for all crew members of trains involved in accidents.

-The constitutionality of congressionally required sentencing guidelines that have been struck down in federal courts across the country creating havoc in the criminal justice system.

-The constitutionality of state laws allowing use of the death penalty against 16- and 17-year-olds. The issue was considered by the court last year, but the justices were unable to definitively settle the matter.

-Whether states can use racketeering laws to shut down adult bookstores. Various bookstore owners in Indiana are arguing that so-called RICO laws allowing seizure of property prior to conviction violate their First Amendment right of free speech.

"I think there is good reason to be concerned about the kind of cases on the court's docket this term," said Marsha Levick, executive director of the legal arm of the National Organization for Women.

"There is ample opportunity for the court to chip away at Title 7 (a law prohibiting job discrimination) and narrow affirmative action opportunities. . . . Kennedy has not been generous in his reading of the civil rights statutes."

Many court watchers feel that Kennedy is much more conservative than the man he replaced but are reluctant to make predictions based on the handful of cases he participated in after joining the court in February.

Howard said there are only fragments to look at with Kennedy but that he was a "dependable conservative vote, more dependable than probably Justice Sandra Day O'Connor. It that's the case, you have the making of a conservative majority."

He added that while O'Connor "has streaks of independence" in some cases dealing with sex discrimination and church-state issues, they are only occasional departures from the conservative bloc.