Can a judge retroactively apply a statute mitigating punishment to a final judgment?

On appeal, respondent urges us to affirm the trial court's order on the basis of this distinction between final and non-final judgments, arguing that the separation of powers doctrine precludes a court from retroactively applying a statute mitigating punishment to a final judgment. (Citing Perez v. Roe 1 (2006) 146 Cal.App.4th 171, 176-177; Superior Court v. County of Mendocino (1996) 13 Cal.4th 45, 53.) Appellant, by contrast, argues that the equal protection clause controls the outcome of this appeal and mandates that he be afforded the benefit of the January 2010 amendments notwithstanding that the judgment against him became final in 2008.