An Oct. 30 report on Supreme Court transitions incorrectly said that President Dwight D. Eisenhower appointed Justice William J. Brennan Jr. during a congressional recess after Brennan's predecessor died. The justice whom Brennan replaced, Sherman Minton, retired for health reasons. (Published 11/6/04)

The news that Chief Justice William H. Rehnquist has thyroid cancer was the first concrete indication that oft-repeated predictions of change at the Supreme Court may come true, but it challenged a common assumption: that any transition would take place on a schedule set by one or more justices.

The most orderly succession would begin with a retirement at the end of a court term in June, followed by confirmation of a new justice and the resumption of business as usual by a full bench of nine the first Monday in October. That is what happened with the last two vacancies, in 1993 and 1994.

Now, however, the chief justice's future hinges on the unpredictable course of a serious disease. And previously unmentionable possibilities -- that Rehnquist, 80, might die in office, remain on the court in a weakened state or be obliged to retire in mid-term -- no longer seem so remote.

The prospect of a shorthanded or otherwise disrupted court cannot be ruled out, especially if the confirmation battle over a successor turns as ugly as the last four years of Senate fights over appeals court nominees have been.

The chief justice left the National Naval Medical Center in Bethesda yesterday and plans to return to the bench on Monday. When the court refused to put Ralph Nader on the Ohio ballot Tuesday, Rehnquist participated in the decision.

Yet if Rehnquist's health deteriorates rapidly, "that kind of orderly scheduling isn't going to happen," said David N. Atkinson, a professor of political science and law at the University of Missouri at Kansas City who has studied Supreme Court transitions. "When events happen on a short timetable, the unexpected can happen in Supreme Court history."

If Rehnquist's position were to become vacant before Jan. 20, when the next presidential term begins, President Bush would have the authority to nominate a successor whether or not he is reelected on Tuesday. White House aides have a full list of Supreme Court candidates vetted and ready to go, though it has not yet been narrowed down to one or two finalists, former Bush administration officials who took part in the process said.

If the Senate were not in session, Bush could fill the seat through a recess appointment. That justice would remain on the bench until the end of the next Senate session -- unless, upon its return from recess, the Senate confirms or rejects the Bush nominee or, if Kerry becomes president, confirms someone else.

Bush has used recess appointments to put judges Charles W. Pickering Sr. and William H. Pryor Jr. on the federal appeals court. Two of the Supreme Court's most distinguished members, Chief Justice Earl Warren and Justice William J. Brennan Jr., were recess appointees, installed by President Dwight D. Eisenhower after their predecessors' deaths and confirmed by acclamation when the Senate returned.

NARAL Pro-Choice America, an abortion rights group that closely follows court nominations, has e-mailed supporters to warn of a "November Surprise": Rehnquist would step down and Bush would replace him with a recess appointee rather than let an eight-member court rule -- and possibly split 4 to 4 -- on an election dispute.

The White House dismissed the e-mail, which was based on an anonymously sourced item that appeared on U.S. News & World Report's Web site.

"The president's thoughts and prayers are with the chief justice, and he wishes him a speedy recovery," White House spokeswoman Claire Buchan said. "We won't speculate on anything other than that."

Republicans knowledgeable about the administration doubt that Bush would attempt a recess appointment if he is reelected. They said that he resorted to recess appointments for appeals judges only after he tried the normal route and was thwarted by Democratic filibusters.

"A recess appointment would generate enormous ill will on the Hill, which would cost votes on the floor later on," said Bradford Berenson, a former associate White House counsel who worked on judicial nominations.

If the chief justice's seat were left vacant for any significant period, however, it could complicate the internal workings of the court. There would still be a quorum of at least six justices, but the court would face the constant prospect of 4 to 4 votes, which automatically affirm the ruling of the lower court without creating a legal precedent.

A prolonged vacancy might also inhibit plans other justices would have to retire, since they might be reluctant to leave the court even more shorthanded.

The chief justice's duties include presiding over oral argument and the court's weekly closed-door conferences. If Rehnquist leaves the court or cannot perform these duties because of his health, the senior associate justice, John Paul Stevens, 84, would take his place.

The 25th Amendment to the Constitution sets up a mechanism by which a president who has become incapacitated can be temporarily or permanently relieved of his duties, but there are no comparable legal provisions for the justices. That has led to difficult situations in the court's past.

Probably the most famous such episode occurred in 1975, when Justice William O. Douglas lingered at the court for most of the year after suffering a debilitating stroke on Dec. 31, 1974. His refusal to step down despite obvious mental and physical problems led colleagues to decide secretly to stop counting his vote in some cases, until he finally quit at the insistence of his wife and friends.

Rehnquist's friends and court analysts said he would never put the court in such a position, in part because he experienced the Douglas episode firsthand, as an associate justice.

"He knows what can happen and what a terrific burden on the court someone can be if he lingers too long," Atkinson said.

All that is known for certain about the chief justice's illness is that he entered the hospital on Oct. 22 and had a tracheotomy related to the thyroid cancer diagnosis last weekend.

The court has released no other information about his condition, or about how and when he learned he was ill.

There are several kinds of thyroid cancer, ranging from relatively treatable varieties to a fast-growing and fatal malignancy known as anaplastic thyroid cancer, which occurs most commonly among men over 65.

In published reports this week, medical experts said the fact that surgeons gave the chief justice a tracheotomy, opening a hole in his throat to relieve a blocked windpipe, could be a sign that the cancer had spread and was hampering his breathing.

Also, the hoarseness from which the chief justice has been suffering recently is often symptomatic of thyroid cancer pressing on nerves in the throat, doctors said.

Rehnquist apparently looked in normal health as recently as mid-September. An old friend who ate a meal with him did not notice anything unusual, according to the friend, who asked not to be identified because of their relationship.

But another friend who saw Rehnquist in mid-October said "he looked terrible and sounded terrible." By the first week of October, the chief justice was concerned enough about his voice to cancel a long-planned speaking engagement at the University of Nebraska Law School, according to the school's dean, Steven L. Willborn.

In a letter to Willborn, Rehnquist said he had been having trouble with his throat and voice, and would not be able to give the lecture Oct. 29 as planned. He added that his physician did not know what was wrong, but that he was planning to have a magnetic resonance imaging (MRI) test in the second week of October.

Rehnquist offered to reschedule his visit for the next year, Willborn said.

The current Supreme Court posed for a group photo in December 2003. Seated, from left, are Antonin Scalia, John Paul Stevens, Chief Justice William H. Rehnquist, Sandra Day O'Connor and Anthony M. Kennedy. Standing, from left: Ruth Bader Ginsburg, David H. Souter, Clarence Thomas and Stephen G. Breyer. Friends of Chief Justice William H. Rehnquist say he is sensitive to the possibility of disrupting the operations of the Supreme Court. After Justice William O. Douglas suffered a serious stroke on Dec. 31, 1974, colleagues stopped counting his vote in some cases.