ON Nov. 6, Americans will not only be electing a president, they'll be choosing a legal path for the nation which will likely last long after the next president is out of office.
That chief executive could well be charged with replacing up to five members of the Supreme Court who may retire because of age.
The issue is vital. It deserves debate during the campaign. President Reagan and his Democratic opponent should lay out for the electorate what they believe to be the court's key role and the type of individual they would nominate to sit on the nation's highest tribunal. The candidates should also pledge that professional qualifications will upstage political considerations in their choices.
The Senate, in reviewing Supreme Court nominees for confirmation, should hold the next president to these standards.
Meanwhile, key issues, such as criminal justice, should not be used by either side as a political football. They are just too important to the well-being of the nation to serve partisan ends.
Obviously, a chief executive could be expected to choose jurists who mirror his own views. Mr. Reagan might be expected to tap someone who is pro-business, who advocates government decentralization, and who is wary of social experiments. His less conservative Democratic opponent would almost certainly lean toward a brand of justice that focuses more on rights for the individual than the group and on a system that places civil liberties over government efficiency.
This is fine -- as long as the Constitution remains the constant, prevailing guideline. Retired Associate Justice Potter Stewart called the Constitution his only ''boss.'' Mr. Stewart, a middle-of-the-road Republican, voted not party - but conscience. Others would do well to follow his example.
Right now, the Supreme Court strikes a delicate balance between liberals and conservatives -- with moderates often casting the deciding votes. But this could all change, with new appointees.
Early in the race for the White House, Sen. John Glenn (D) of Ohio called the appointment of high court justices ''one of the great issues in this presidential campaign.'' Senator Glenn warned fellow Democrats that President Reagan, if reelected, would ''remake the Supreme Court'' in line with his conservative ideology. Other candidates, both Democrats and Republicans, have been surprisingly quiet on the subject.
One of the justices himself, however, John Paul Stevens, has rung an alarm about the present court's direction in criminal cases. Justice Stevens cited a distinct tilt by the court toward prosecutions. He intimated that his colleagues were responding to anticrime sentiment on the part of the public rather than adhering strictly to the Constitution.
''The Court must be ever mindful of its primary role as the protector of the citizen and not the warden or the prosecutor,'' he elaborated. ''The framers surely feared the latter more than the former.''
Justice Stevens's remarks came in dissent to a search-and-seizure decision in a Florida appeal, in which the high court reinstated a conviction that had been thrown out by a lower court because a search of an automobile had been conducted illegally. Justices William J. Brennan Jr. and Thurgood Marshall -- two of the court's most liberal members -- joined this view.
Justice Stevens further noted that this case was decided summarily - that is, in an unsigned opinion and without oral arguments and a full briefing. He stressed that, since 1981, the Supreme Court has decided in favor of ''the warden or the prosecutor'' in 19 such summary rulings on cases involving constitutional rights of people accused of crimes. This, Justice Stevens said, ''poses disturbing questions concerning the Court's conception of its role.''
Recent written decisions by the court permitting searches in factories for illegal aliens and police entry into privately owned fields to search for marijuana seem to back up Stevens's claim. Dissenting justices stressed that both decisions clash with constitutionally guaranteed privacy rights.
A further reading - and probably the most significant one -- on how the Supreme Court sees its role in the area of criminal justice could come later this spring with key rulings on cases involving the so-called exclusionary rule. The Reagan administration is urging the court to modify a 70-year-old practice of excluding evidence in a criminal proceeding if the evidence has been obtained by police using improper procedures.
The exclusionary rule and the death penalty appear to be the two criminal justice issues that most polarize the public politically. Conservatives, in opposing the former and backing the latter, insist that the entire system needs to be brought back into balance -- with more emphasis on the rights of the innocent and less on those of the criminal or the accused. Liberals, on the other hand, stress that guarantees of the rights of individuals are paramount -- and must not be set aside, whatever the costs.
Some suggest that the November election could, in effect, become a referendum on the Constitution -- and how it should be interpreted. There's nothing wrong with that.