What is the case law for reducing the sentence of first degree murder to second degree?

Smith next argues that the rationale of People v. Dillon (1983) 34 Cal.3d 441, 477, 194 Cal.Rptr. 390, 668 P.2d 697 should be applied to reduce his conviction from first to second degree murder. He asserts the punishment for first degree murder is disproportionately severe as applied to a non-triggerman such as himself who did not intend to kill and whose murder conviction is based solely on the felony-murder rule.