Resentencing is not automatic. The measure gives judges discretion to consider a host of factors to determine whether an offender poses an “unreasonable risk” to public safety and should remain in prison. Those factors include the types of previous crimes, injuries to victims, lengths of prior prison terms, disciplinary and rehabilitation records in prison, and any other evidence the court deems relevant.
Opponents of Prop. 36 have argued that the measure was unnecessary because judges already have discretion to impose lighter sentences. They also criticized the initiative for allowing inmates who committed violent crimes prior to their final strike to qualify for possible release.
Thorpe said the measure is putting a heavy burden on prosecutors to pull together all the pertinent records to determine the level of risk an offender poses.
“The district attorneys have that responsibility for saying, ‘Hey, this guy is or is not a danger to public safety,' ” he said.
Public defenders' offices around the state also are bracing for a heavy workload, especially if a large number of petitions are challenged.
"The costs could grow significantly," said Laura Hoffman, chief deputy public defender for San Bernardino County.
Prop. 36 provides little guidance on how the petition process should be conducted, though it specifies that inmates must file their petitions by November 2015. In recent weeks, prosecutors and defense attorneys around the state have been working with corrections officials to create a system to locate, copy and transfer inmates' prison records to local courts assigned to evaluate the petitions.
In some cases, the records go back decades and are kept only on paper. In San Bernardino County, prosecutors have filed subpoenas seeking records on 16 inmates, according to corrections spokeswoman Terry Thornton.
Santa Clara County District Attorney Jeff Rosen, who publicly supported Prop. 36, said his office also is requesting prison records for all third-strike inmates seeking new sentences. Rosen said that of the 120 to 130 inmates who likely will qualify under the measure, more than half could win reduced sentences, leaving a significant minority that will remain behind bars for the duration of their terms.
“I believe that Proposition 36 balances individual fairness with public safety,” Rosen said.
District attorneys in Orange and Kern counties declined to comment on how they were implementing Prop. 36.
But lawyers representing third-strikers expressed concern that challenges over prison records could create a bottleneck in the petition process and long delays for some inmates who are eligible for release. Michael Romano, a Prop. 36 co-author who directs a law clinic at Stanford University, said another challenge is ensuring that every inmate who qualifies under the statute receives adequate representation and has a transition plan for life after prison.
"Their lives are on the line," he said. "This is their last, best chance of getting out of prison, reuniting with their families and getting to put their lives back together."
While some petitions might be unopposed, Romano said, a "large number of cases are going to be contentious."
"We are not expecting that prosecutors are going to roll over," he said. "We are loading for bear."

Michael Montgomery is an investigative journalist for California Watch and KQED News.