The US Supreme Court - which legal observers have labeled an ''activist'' tribunal - could enhance this reputation with landmark decisions this term in the areas of criminal justice, civil rights, and church and state relations.
The curtain lifts on the 1983-84 session this week with 112 cases already set for argument. The range of issues include sex discrimination, restraints on business, capital punishment, and state involvement in religious exercises.
Observers say the court could significantly change the course of American jurisprudence if it (1) decides to adopt a ''good faith'' exemption of the exclusionary rule, a 70-year-old guideline affecting the admissibility of police-gathered evidence in court; (2) reverses several decades of affirmative-action policies in the hiring and firing of municipal workers; and ( 3) chips away more of the ''wall of separation'' between church and state by allowing some form of public prayer in the schools and by permitting cities or states to sponsor religious displays.
Highly controversial cases involving these issues are on the docket or are likely to be added as the court adjusts its final calendar.
The court is heavy on seniority. Eight justices have served longer than the historical average of 11 years and some may be considering retirement. Only Justices John Paul Stevens and Sandra Day O'Connor have served less time. Among those rumored to be considering retirement is Chief Justice Warren E. Burger.
Constitutional scholars predict that whoever is elected to the White House next year could have the opportunity to appoint at least four new justices by 1988 and determine the court's dominant direction. So far, Mrs. O'Connor, the high tribunal's first woman member, has been President Reagan's only appointee. Scholars say her early opinions seem compatible with the President's social policies and philosophy of judicial -restraint.
Some analysts say that if Mr. Reagan for some reason decides not to seek reelection or if his ability to win a second term is in doubt, senior conservatives on the court could decide to retire before the end of 1984 - giving the President the opportunity to seat one or more justices who agree with his philosophy.
Supreme Court experts now tend to agree that although recent decisions show the current court leans ''right of center,'' the tribunal still exhibits marked judicial independence. A major test of this independence may come this term, however, when an unusually large number of cases on appeal come with administration briefs. The White House is urging a tougher stance toward criminals and the accused, less government intervention in civil rights matters, and a lifting of the yoke of regulation from business, particularly in antitrust laws.
In reference to several business-related cases on the new docket, Bruce E. Fein, who conducts an annual review of significant Supreme Court decisions for the conservative American Enterprise Institute, says the fact that the high court has agreed to review these cases indicates ''a willingness to reexamine long-held antitrust doctrines'' and ''expand the freedom of businessmen'' to engage in commerce ''without being liable to treble damages.''
In examining forthcoming criminal-justice cases, Mr. Fein says he expects the court to modify the exclusionary rule to allow evidence to be presented in court even if police have inadvertently, or in ''good faith,'' violated a suspect's rights while obtaining that evidence. Now any such breach of police procedure means the evidence can be excluded or even that the charges may be dropped on procedural grounds.
''This court frowns on criminal law that deters from the primary objective of determining guilt or innocence,'' Fein says.
This trend, or philosophy, alarms advocates of individual rights. John Shattuck of the American Civil Liberties Union says proposed modification of the exclusionary rule could lead to ''erosion of Fourth Amendment rights (protecting the accused).''
Harvard University legal scholar Laurence Tribe assesses that the court is trying to ''correct what it sees as extravagant extensions of individual rights'' written into law by former tribunals and now under attack by political conservatives who are demanding more justice for ''victims'' and less emphasis on protecting suspects.
These are the key issues, as seen by experts, coming before the court this term:
Criminal justice. There are 30 cases set for oral argument involving police warrants, search and seizure laws, the death penalty, limits on the federal courts in reviewing constitutional cases already decided by state tribunals, probationers' confessions, and use of bribery laws. Three deal with the proposed ''good faith'' exception of the exclusionary rule. Last term, the court unexpectedly sidestepped the issue. But this time, some ruling - perhaps a very narrow one - is expected. Meanwhile, Congress is anxiously looking on, considering its own legislation in this area. This issue is almost certain to be debated in the 1984 presidential race.
Civil rights and discrimination. Key cases involve a federal law that bans sex discrimination in federally funded programs, and laws dealing with affirmative action or racial quotas in public hiring. In Grove City College v. Bell, the Reagan administration advocates that withholding of federal funds for a school's discriminatory practices should be limited to particular programs and not applied to the school in general. Grove City, a small private college in Pennsylvania, insists it doesn't discriminate. But it argues that because it gets no direct federal aid (the aid goes to the students), it should not be subject to government regulations.
In a Memphis case - paralleling a Boston reverse-discrimination police case which the court refused to decide last year - white firefighters claim they were victims of discrimination when they were laid off beforeless-tenured blacks as a result of fiscal cutbacks by the city.
If the court agrees with the firefighters, the decision could mark an end to affirmative action and quotas to achieve racial balance in public jobs.
Separation of church and state. The court is expected to resolve a Pawtucket, R.I., case that will determine whether government-sponsored Nativity scenes violate First Amendment guarantees of separation of church and state. Municipalities across the nation await this decision, which is expected before the Christmas season. Observers say Pawtucket could be a landmark decision in church-state relations. Later in the term the court may also take on a cluster of controversial ''moment-of-silence'' school prayer cases. Until now, the high tribunal generally has ruled religious observance in schools as unconstitutional.