THE Supreme Court, in its first year under Chief Justice William Rehnquist, has again shown how the court has a momentum of its own. Efforts to alter the course of justice in either a liberal or conservative direction, by appointments and elevations, are resisted. This has been the case through the Reagan era, which has produced two new appointees - Sandra Day O'Connor and Antonin Scalia - and has replaced Warren Burger with Mr. Rehnquist. Rehnquist has brought a quicker pace, a more open and energetic style, to the court's deliberations. Justice O'Connor has made her own niche in her decision-making, and Justice Scalia has brought a provocative inquisitiveness to the court's public sessions. But the standout in this session has been Justice William Brennan, a veteran liberal who has made his presence felt by writing a number of majority opinions and incisive dissents.
This basic momentum of the court and the unpredictability of its members' performance should be kept in mind when anticipating the effect of Justice Lewis Powell's announced retirement. Mr. Powell has often held the swing vote in key decisions. The Reagan administration will have the opportunity to replace him; but the new Democratic majority in the Senate holds enough votes to make sure that any successful candidate have a distinctive record and be within responsible bounds in legal interpretation. Time is short for the administration to take new issues to the court; and it has done poorly, except in criminal matters, on those it has pushed thus far.
In the main, the Rehnquist court has given little reason to fear further change. To its credit, it has advanced individual rights and liberties. In social policy, job rights of women granted pregnancy leave were protected, affirmative-action plans for blacks upheld. These decisions reflect progressive impulsions in society to raise the threshold of fair opportunity.
Unfortunately, the court also seemed to follow the current public inclination to get on with the executions of prisoners on death row. Searches of employees' desks were sustained. And in one of the last of its nearly 150 decisions, a narrow majority ruled that military servicemen could not sue superiors or the government for even the grossest violations of their basic rights - in a case involving experiments with the drug LSD on hundreds of unsuspecting soldiers. As Justice O'Connor said in her dissent, the military's conduct was so far beyond the ``the bounds of human decency ... it simply cannot be considered a part of military discipline.''
The court reaffirmed the separation of church and state: It objected to the Louisiana Legislature's attempt to require the teaching of ``creationism'' in science classes; it ruled that religious organizations should be free of government interference in certain hiring matters.
Especially when members step down, and as presidential elections approach, speculation abounds about whether the Supreme Court will sustain its constructive record.
But this can be said for now: In the year of the observance of the US Constitution's 200th anniversary, the interpreters of that document have performed, under Mr. Rehnquist's leadership, in a manner that reaffirms its vitality and continuing relevance.