A majority of the U.S. Supreme Court seemed willing Tuesday to uphold a federal court panel's authority to order California to reduce the population of its crowded prisons as a step toward improving its woeful health care system for inmates.

In more than an hour of arguments, some justices suggested they would narrow the San Francisco-based panel's August 2009 order that required the state to transfer or release 40,000 prisoners in two years.

But the state's arguments - that the release order exceeded judicial authority, was unnecessary to improve prison health care and could endanger Californians - drew skeptical responses from at least five of the nine justices...

In a major test case, lawyers for California prisoners allege their clients are kept in such overcrowded conditions that they should be released, rather than continue serving sentences that fall under the constitutional ban on cruel and unusual punishment. The U.S. Supreme Court began hearing the case today, in a proceeding likely to shine a spotlight on the nation's controversial incarceration system.

A panel of federal judges ruled last year that the overcrowding in California prisons constituted a violation of the Eighth Amendment's protections against cruel and unusual punishment. The judges ordered California to release 40,00 inmates over two years.  But lawyers for the state appealed, leading to the Supreme Court's hearing.

Lawyers for the prisoners argue in court papers that California's prisons are housing twice as many prisoners as they were built to contain, and as a result, the safety of prisoners, guards, and prison personnel is in jeopardy...

California, under pressure to reduce the number of inmates in its crowded prisons, has steadily increased the number of convicts it sends to private institutions outside the state since Gov. Arnold Schwarzenegger began the program in 2006.

The latest deal will ship another 5,800 inmates to private prisons across state lines, bringing the total to more than 15,000. The transfers will begin in May under a contract that runs through June 2013 - nearly halfway through the term of Gov.-elect Jerry Brown.

California has a prison population of about 164,000 people, but its corrections facilities are only equipped to house around 100,000. The state is under court order to reduce the inmate population by 40,000 though state officials are challenging the order, and the U.S. Supreme Court will hear arguments in the case today...

The suicide rate in California's overcrowded prisons is nearly twice the national average, and one inmate dies every eight days from inadequate medical care.

These are just two indicators cited in the 15-year legal battle over whether the state's prisons are failing to provide humane medical care for the 165,000 inmates.

On Tuesday, the problems of California's prisons will move to a national stage when the Supreme Court hears the state's challenge to an extraordinary court order that would require the prison population to be reduced by about 25% in two years. That could mean releasing or transferring more than 40,000 inmates, state lawyers say...

Here's something even prison guards and inmates agree on: a court order cutting California's inmate population by about 40,000.

A three-judge panel in a California federal district court ruled in January that overcrowding in the state's prison system, the nation's largest, is the main cause of substandard medical and mental health care that violates prisoners' Eighth Amendment right to be free from cruel and unusual punishment.

Overcrowding at a state prison in San Diego last year led authorities to house inmates in the gymnasium.

That ruling is set to be reviewed by the U.S. Supreme Court, with arguments scheduled for Tuesday...