Unfortunately, this has happened from time to time in the Court’s history, particularly given the advanced age of many of the justices. There is no particular rule that comes into play when a justice becomes incapacitated. No rule forces a justice to resign. Periodically, measures have been introduced in Congress to try to pass legislation forcing the involuntary retirement of justices when they have become mentally incapacitated. U.S. senator Sam Nunn of Georgia introduced such a measure in the 1970s.

Sometimes, a justice’s colleagues may try to suggest that the justice take time off or even step down. Toward the end of their careers, some justices allegedly have lost much of their effectiveness. Reportedly, Justices William O. Douglas and Thurgood Marshall, for example, were ineffective and shadows of their former selves.

Most often, the justice may take a break and hopefully recover. For example, when Chief Justice William Rehnquist had cancer surgery, Justice John Paul Stevens—the most senior associate justice—presided over the Court.