70 Cal.2d 15 (Cal. 1968) Cited 1,303 times
Holding that a “verdict of murder in the first degree on a theory of a wilful, deliberate, and premeditated killing is proper only if the slayer killed as a result of careful thought and weighing of considerations; as a [d]eliberate judgment or plan; carried on coolly and steadily” (citations, internal quotation marks, and alterations omitted)