California's prisons are so overcrowded that the state is violating inmates' constitutional rights, three federal judges ruled today in a decision imposing a cap on the prison population that will force the state to release nearly 43,000 prisoners over the next two years.

The 185-page opinion also accused the state of fostering "criminogenic" conditions, compelling former prisoners to commit more crimes and feed a cycle of recidivism.

The effect of the judges' ruling in two inmate challenges to their conditions dovetails with early-release proposals aired during last month's heated budget debate in the state Legislature as lawmakers sought to close a $26.3-billion deficit.

The ruling by three federal judges stems from challenges by two inmates alleging that the state's network of 33 prisons is so overcrowded that they are denied adequate health care and treatment of mental illnesses.

California's prisons, designed to hold 84,000 inmates, house 158,000, much of the overflow contained in converted sports facilities arrayed with triple-tier bunks. That exposes prisoners to infectious diseases, the lawsuits alleged, constituting cruel and unusual punishment in a system suffering a shortage of doctors, nurses and technicians.

U.S. District Judge Thelton Henderson seized oversight of the prison healthcare network in 2006 and put a court-appointed receiver in place to carry out a thorough reform of the system, in which inmates were dying of curable or avoidable conditions at the rate of one a week. The current receiver, Clark Kelso, said in a recent interview that his staff was making progress in upgrading antiquated medical records-keeping and medication-dispensing, but that the fruits of those projects remained at least a year away.

In late July, during the heated debate over how to close a $26.3-billion shortfall in the state budget, California lawmakers passed $1.2 billion in cuts to the state prison system that envisioned some early releases of inmates. But they put off deciding specific details amid harsh resistance by law-and-order advocates who fear any mass release of prisoners would endanger public safety.

In a preliminary ruling issued by the three judges in February, the state was advised to reduce the prison population by about a third, meaning as many as 57,000 inmates would have to be moved out of the state facilities over a two- to three-year period.

Atty. Gen. Jerry Brown denounced the earlier ruling as "the latest intrusion" of the federal courts into the state's affairs, and he is expected to appeal today's ruling.