In the summer of 1990, Supreme Court Justice William Brennan retired and President George H.W. Bush named US Court of Appeals Judge David Souter to succeed him. A few days later, Justice Thurgood Marshall fumed about the Souter nomination in an interview with ABC News correspondent Sam Donaldson.

“When his name came down, I was listening to television,” Marshall said. “I called my wife and said, ‘Have I ever heard of this man?’ She said, ‘No.’ ” Marshall declared disdainfully that he didn’t have “the slightest idea” why Bush had nominated Souter. He could say nothing good about the president — in fact, he told Donaldson, “I consider him dead.”

It was an embarrassing and unbecoming performance, and it exposed to public view what court insiders already knew: The once-formidable Marshall, then 82, was in serious decline — not only physically, but mentally. “Some people watching that interview,” Donaldson said when it aired, “will think that … he’s lost it.”

He may not have fully “lost it,” but clearly Marshall was no longer a fully-engaged Supreme Court justice. He spent hours watching daytime TV and telling stories, leaving the writing of his opinions to law clerks. In his prime, Marshall had been a masterful litigator and the civil rights movement’s indispensable legal strategist. But by 1990 he “seemed uninformed and disengaged,” as one of Justice Lewis Powell’s clerks later wrote. Another former clerk recalled, “Marshall was no longer up to his responsibilities, or even the appearance of being up to them.”

Elena Kagan’s confirmation hearings before the Senate Judiciary Committee this week are largely a formality; barring the unexpected, the 50-year-old solicitor general will become the 112th Supreme Court justice. Under the Constitution, that position, and the extraordinary authority that goes with it, will then be hers for as long as she chooses to keep it. Kagan clerked for Marshall in the late 1980s, when he was already “in his decline and alienated, marginalized,” as his biographer Juan Williams observed last month. It may have pained her to see a man she greatly admired cling to power well past the point when he should have let go. But there is nothing to stop her from doing the same thing.

Too many justices have. Chief Justice William Rehnquist refused to retire even as he was dying of a severely debilitating thyroid cancer. A stroke left Justice Hugo Black increasingly confused, his memory and focus badly impaired, yet he stayed on the bench until just days before his death. Justice William O. Douglas, also ravaged by a stroke, began dozing during oral arguments and slipping at times into near-incoherence; only after 10 months of this did he finally agree to depart.

“Mental decrepitude among aging justices is a persistently recurring problem,” wrote historian David J. Garrow in a detailed analysis of the issue in 2000. “The history of the Court is replete with repeated instances of justices casting decisive votes … when their colleagues and/or families had serious doubts about their mental capacities.” Worse yet, “mental decrepitude has been an even more frequent problem on the 20th-century court than it was during the 19th.”

The Constitution’s framers thought life tenure necessary to safeguard judicial independence, but they didn’t foresee how immensely powerful the Supreme Court would become. Nor could they have predicted that the American life span, which averaged around 40 in their day, would lengthen so dramatically over the next two centuries. Had they known that justices would grow entrenched, hunkering down on the court for two or three decades, often into advanced old age with all its deteriorations, it is doubtful that life tenure would have struck them as such a good idea.

No other major democracy grants limitless terms to its supreme court judges; neither does any state except Rhode Island. Most Americans support an end to lifetime tenure, and the Constitution should be amended to reflect that. Supreme Court justices, as a number of legal scholars have proposed, should be limited to a single 18-year term, with their terms staggered two years apart. We don’t allow presidents to hold office for life. Isn’t it time we stopped permitting Supreme Court justices to do so?

© Copyright 2010 Globe Newspaper Company.