Chief Justice William H. Rehnquist (search), ailing with thyroid cancer (search), went to the hospital over the weekend after experiencing breathing problems but returned to the bench Monday.

Rehnquist, 80, was taken by ambulance Sunday to Arlington Hospital in suburban Virginia after developing a problem with the tracheotomy tube (search) that helps him breathe. He was treated on an outpatient basis, said Ed Turner, the court's deputy spokesman.

No other details were provided.

Rehnquist disclosed in October that he has thyroid cancer and underwent a tracheotomy. The procedure involves inserting a tube to aid breathing.

He returned to the bench last week after a five-month absence, though he had continued working at home and at the court during his convalescence.

Rehnquist sat for arguments Monday and was active, asking a number of questions of lawyers who debated an international death penalty case.