Attorneys for the state and inmates' rights groups clashed Tuesday at the opening of a high-stakes trial over whether California's jam-packed prisons have led to unconstitutionally poor medical and mental health care.

If the special panel of three federal judges rules against the state, another trial will be held next year to determine remedies. Possible solutions include an order to release inmates before they have completed their full sentences, a move opposed by the Schwarzenegger administration.

Attorneys for the inmates want the prison population reduced from about 156,300 inmates to 110,000.

Further delay in solving California's prison crowding will mean only "additional pain, suffering and death for our clients," Michael Bien, one of the attorneys representing inmates, said during Tuesday's hearing.

"The California prison system is dangerous and broken," he said.

At issue is whether overcrowding is the leading cause of medical and mental health care that the federal courts already have found to be substandard — and in some cases so negligent that it has directly contributed to inmates' deaths.

The Schwarzenegger administration says steps already are being taken to reduce the population and an early release plan would endanger the public.

The state argues there are many causes for poor inmate health care, not just crowding, and that conditions are improving without releasing inmates.

Paul Mello, an attorney for the state, said California's spending on inmate medical care has increased from $345 million in 1995 to nearly $2.2 billion today. The amount spent per inmate on medical care has grown from $2,700 to nearly $14,000 a year, Mello said.

"The state has put its money where its mouth is," he said. "There have been significant improvements."

Attorneys representing inmates cited national experts who have found that overcrowding is aggravating efforts to improve medical care in the state's prisons.

The hearing in San Francisco is expected to last through mid-December, but it's not clear when the panel will rule.

Republican lawmakers and law enforcement officials already are planning their appeal to the U.S. Supreme Court if the panel orders inmates to be released early.