But it was not clear that a majority was ready to endorse an order by a special three-judge federal court there requiring state officials to reduce the prison population by as many as 45,000 inmates over two years, to address what it called longstanding constitutional violations in medical and mental health treatment.
Justice Stephen G. Breyer said the conditions documented in court papers were horrendous.
He referred, for instance, to a passage in one brief describing prisoners “found hanged to death in holding tanks where observation windows are obscured with smeared feces, and discovered catatonic in pools of their own urine after spending nights locked in small cages.”
But Justice Anthony M. Kennedy, whose vote may determine the case, said the special court’s math seemed arbitrary, and Justice Samuel A. Alito Jr. said he feared a rise in crime should large numbers of prisoners be released.
Carter G. Phillips, a lawyer for the state, said the special court had acted rashly in ordering the prisoner reduction. Mr. Phillips said the state was making progress but needed more time to address what Gov. Arnold Schwarzenegger called a state of emergency in 2006.
The special court’s order, issued last year, addressed two consolidated class actions. One was filed in 1990, the other in 2001.
“So how much longer do we have to wait?” Justice Ruth Bader Ginsburg asked. “Another 20 years?”
Justice Sonia Sotomayor pressed Mr. Phillips to “slow down from the rhetoric and give me concrete details” about the steps the state was taking to address the problems.
Mr. Phillips pointed to new construction and hiring, out-of-state transfers and early releases prompted by additional good-time credits. He said the state’s prison population had dropped to about 147,000 from a high of about 170,000, at which point the system was at roughly double its capacity.
That did not satisfy Justice Sotomayor. “When are you going to avoid the needless deaths?” she asked. “When are you going to avoid or get around people sitting in their feces for days in a dazed state?”
Justice Antonin Scalia, recalling Justice Sotomayor’s earlier admonition to Mr. Phillips, now repeated it, but with sarcasm. “Don’t be rhetorical,” Justice Scalia said.
Justice Kennedy also seemed frustrated with the pace of progress.
“At some point the court has to say: ‘You have been given enough time. The constitutional violation still persists, as the state itself acknowledges,’ ” he said.
Later, though, Justice Kennedy seemed to question the special court’s decision to impose a cap of 137.5 percent of the system’s capacity. He said 145 percent of capacity might have been as effective and less intrusive.
Justice Alito went further, saying a court order addressing overcrowding was only indirectly connected to poor medical and mental health treatment.
Donald Specter, a lawyer for the prisoners, said that the special court had not ordered anyone to be released and that the state could use other means to reduce overcrowding. Mr. Specter added that possible solutions aimed more directly at the issues in the two class actions had not worked and that only an overall reduction in the prison population would allow humane care to be provided.
The court heard 80 minutes of arguments in the case, Schwarzenegger v. Plata, No. 09-1233, rather than the usual hour.
Mr. Phillips used his three minutes of rebuttal time at the end to underscore the two themes that had seemed to resonate most with the justices whose votes he would need.
“Anytime you say you are going to release 30,000 inmates in a compressed period of time,” he said, “I guarantee you that there is going to be more crime and people are going to die on the streets of California.”
Then he addressed Justice Kennedy’s point about the special court’s arithmetic. “There is not a shred of evidence,” Mr. Phillips said, “that 137.5 makes any sense whatsoever. That is a pulled-out-of-the-air number.”