Rehnquist, who has been absent from the bench for nearly two months, will not vote in cases that were heard in November, unless the remaining eight justices are deadlocked. He does plan to participate in the cases argued in December, Supreme Court spokeswoman Kathy Arberg said.
The announcement came after the Supreme Court released several opinions, including two without Rehnquist's involvement. Monday was the Supreme Court's final work day before a nearly monthlong holiday break.
Rehnquist, 80, has been working from his home in suburban Virginia while undergoing treatment. While he has not heard any arguments since October, he is briefed on the cases and the expectation was he would vote in them.
The court has divulged only the barest details of Rehnquist's condition, though it's known he is undergoing the kind of treatment often used for the most serious type of thyroid cancer. Arberg did not say why Rehnquist decided to bow out of the November cases.
With speculation swirling that Rehnquist could announce his retirement at any time, court observers were caught by surprise Friday when Arberg said Rehnquist had accepted President Bush's invitation to administer the oath of office at the Jan. 20 inauguration.
By tradition, the chief justice swears in the president, and Rehnquist has participated in every inauguration since becoming chief justice in 1986.
Some of the court's biggest cases so far this year were argued in October, when Rehnquist was on the bench. Among them: a challenge to the use of the death penalty for juvenile killers and a case that put in jeopardy the longtime rules for sentencing federal criminals.
Rulings in both of those cases will come sometime after the court returns in January.
A high-profile November case in which Rehnquist won't vote, unless he has to break a tie, deals with standards for on-the-job age discrimination lawsuits.
Rehnquist wrote a 6-3 decision on Monday in a case that was argued Oct. 4, the first day of the Supreme Court's nine-month term. The ruling sidestepped a decision on whether states can refuse to pay for appeals by indigent defendants who plead guilty to crimes. Rehnquist said that two Michigan attorneys who represent poor defendants did not have standing to challenge Michigan's law. The case is Kowalski v. Tesmer, 03-407.
In other decisions Monday, the Supreme Court: