Prospective application of the January 25, 2010 amendment to Penal Code section 4019, which increased the rate at which qualified inmates accrued presentence custody credits, is consistent with Legislative intent. “For eight months during 2010, a now superceded version of section 4019” increased the rate at which qualified inmates accrued presentence conduct credits. Under Penal Code section 3, penal laws are prospective unless the Legislature’s intent to do otherwise is clear. The January 25, 2010 version of section 4019 contained no express declaration it was to be applied retroactively and no such implication arises from extrinsic sources (i.e., legislative history). Nor may retroactivity be inferred from the state’s fiscal emergency that prompted the legislation; the method the Legislature chose to deal with the emergency still involved an increased incentive for good behavior to receive the enhanced credits. Because the January 25, 2010 version of section 4019 applies prospectively, inmates whose presentence custody spanned before and after January 25, will receive credits at two different rates. The rule of People v. Estrada (1965) 63 Cal.2d 740 (when Legislature reduces penalty for a crime the reduction applies in all cases not yet final) does not apply here because former section 4019 does not alter the penalty for a crime – it addresses future conduct by providing increased incentive for good behavior.

Prospective only application of former section 4019 does not violate the equal protection clauses of the state and federal Constitutions. “The important correctional purposes of a statute authorizing incentives for good behavior [citations omitted] are not served by rewarding prisoners who served time before the incentive took effect. . . .” Conduct credits must apply prospectively to motivate good behavior. Thus, prisoners who served time before and after former section 4019 was effective are not similarly situated with respect to the purpose of the law.