I concur in the result. However, I write separately bécause the majority’s excursion into constitutional analysis is both unnecessary and contrary to applicable precedent.
This case can be resolved by applying the well-established principle that statutes are presumed to operate prospectively absent an express legislative declaration to the contrary. The majority opinion does so at page 353 and I agree. That should be the end of the matter. However, the majority go farther by concluding retroactive application of amended Penal Code1 section 1000 et seq. here would violate the constitutional prohibition against ex post facto laws by increasing Perez’s punishment. Specifically, citing People v. Superior Court (On Tai Ho) (1974) 11 Cal.3d 59 [113 Cal.Rptr. 21, 520 P.2d 405], the majority view diversion as a specialized form of “an alternative form of punishment,” to wit, probation.
The majority’s reliance on People v. Superior Court (On Tai Ho), supra, 11 Cal.3d 59, is misplaced. Although containing language referring to diversion as a specialized form of probation, which itself is an alternative form of punishment, On Tai Ho did not address the issue of the distinction between punishment and rehabilitation. Instead, On Tai Ho involved the question whether diversion was a judicial function or a matter within prosecutorial charging discretion. In that context, the Supreme Court determined diversion to be a judicial function based in part on the theory that both diversion and probation were programs authorized and supervised by the court.
Further, the majority’s analogizing probation to section 1000 diversion is inapt. Probation has attendant punitive conditions such as imposition óf custody, community service and required waiver of rights. However, unlike probation, section 1000 diversion has no such attendant punitive elements. Instead, section 1000 diversion constitutes a method to avoid the criminal process entirely by meeting the specified conditions of successfully completing a nonprobation department drug rehabilitation program and staying clean for the designated period. Upon satisfying those conditions, a diverted person literally has the slate wiped clean, a situation unlike the partial relief granted to a successful probationer under section 1203.4.
In sum, while perhaps “disadvantaging” Perez, the new preconditions to diversion in amended section 1000 et seq. did not rise to the level of a violation of the constitutional prohibition against ex post facto laws under *359the analytical tests of Tapia v. Superior Court (1991) 53 Cal.3d 282 [279 Cal.Rptr. 592, 807 P.2d 434]. Hence, had it chosen to do so, the Legislature could have changed those statutory requirements retroactively without running afoul of the ex post facto clause.
A petition for a rehearing was denied December 22, 1998.
All statutory references are to the Penal Code.