Chief Justice William H. Rehnquist (search) is back at work part time at the Supreme Court, but there is no word that he is ready to return to the bench.

Rehnquist missed about 25 court arguments in November and December while receiving chemotherapy and radiation for thyroid cancer. A Supreme Court (search) spokeswoman said Wednesday that the 80-year-old chief justice returned to the building late last month.

"He's been working from both the court and home," spokeswoman Kathy Arberg said.

Few details have been released about Rehnquist's condition. The chemotherapy-radiation treatment is common for the aggressive and life-threatening type of thyroid cancer (search).

"It's pleasantly surprising that he is able to come back to work. It implies that the tumor is somewhat under control," said Dr. Kenneth Burman, a thyroid specialist at Washington Hospital Center who is not involved in Rehnquist's treatment.

The new information about Rehnquist's work schedule sheds little light on whether his retirement is imminent. The court hasn't had a vacancy in more than a decade, a modern-era record, and Rehnquist had been considered the leading prospect to leave even before his cancer diagnosis in October.

The announcement does put to rest speculation that Rehnquist is bedridden, Northwestern University law professor Lawrence Marshall said, and indicates the chief justice, known for his stubbornness, hopes to return to the bench.

"It certainly doesn't surprise me that if anyone would fight hard to continue it would be him," Marshall said. "If he's unable to come back and sit routinely in all cases, he'll ultimately decide it's time to go."

It is unclear if Rehnquist will preside next week when the court returns from the holidays. He has accepted an invitation swear in President Bush on Jan. 20.

Rehnquist had been away from court since Oct. 22 when he was hospitalized and then underwent a tracheotomy to help him breathe. At the time, Rehnquist said he expected to be back at work in a week. He later had to acknowledge that was unrealistic.

Arberg said Rehnquist began coming into the office the week of Dec. 20. She would not say what his working hours are.

The justices' comings and goings are little noticed. They arrive at work through an underground garage, escorted in court cars with tinted windows. Their offices are sealed off from the public.

Rehnquist, who marks his 33rd anniversary on the court on Friday, reduced his work load during his cancer treatment. He is not participating in decisions from the dozen cases heard in November -- in the early days of his treatment -- unless the remaining eight justices are deadlocked. He is expected to take part in the December cases, relying on briefs and transcripts of the arguments.

The University of Arizona was notified this week that Rehnquist would not be able to teach there this year. He has taught a two-week class at the university for the past decade, usually in February.