Arizona v. Correll
In Arizona v. Correll, 148 Ariz. 468, 715 P.2d 721 (Ariz. 1986) the defendant was convicted, inter alia, on three counts of first-degree murder and sentenced to death.
At the time of the trial, a newly enacted aggravating factor permitted juries to consider that "the defendant has been convicted of one or more other homicides . . . which were committed during the commission of the offense." 715 P.2d at 734.
The aggravator, however, was not enacted until after the commission of the homicides.
The court found that the statutory amendment to the death penalty law was substantive in nature rather than procedural and that the defendant could be disadvantaged if the aggravator were to apply as against him. 715 P.2d at 735.
Accordingly, the court held that application of the new aggravator would be an ex post facto law and could not be constitutionally upheld. Id.