How have courts reduced a convicted first-degree murderer's sentence to second-degree murder?

from the situation without panicking. (People v. Dillon, supra, 34 Cal.3d at pp. 450, 488.) Additionally, his coparticipants in the underlying crime, who could have been liable for the killing as aiders and abettors, received only minimal punishment; none was convicted of any form of homicide. (Id. at p. 488.) For these reasons, the court held punishment as a first degree murderer with life imprisonment was cruel or unusual, and it reduced the defendant's conviction to second degree murder. (Id. at p. 489.)