[2] The most significant departure was the division of murder into degrees, a change initiated by the Pennsylvania legislation of 1794.
Up until the 1960s, the common law definition of 'murder' was intentional homicide with malice aforethought; i.e. it was codified without respect to distinct elements as it is today.
First degree murder in this epoch of criminal law, and in Pennsylvania at the time the statute of 1794 was ratified, was reserved for intentional homicide whereby the conduct was 'willful', 'deliberate', or 'premeditated'.
Because the assignment of first (or second) degree murder to a given defendant was, in a sense, randomly chosen by the jury rather than adhered to by a strict set of codes or defined elements of a crime, the argument, asserting that the levying of a capital punishment in the absence of given set of procedures fundamentally conflicted with the notions embodied by due process, gained prominence, and the constitutional legitimacy of capital punishment for certain offenses or offenders was challenged in subsequent Supreme Court cases.
"[3] The statute provides that "[c]riminal homicide constitutes murder of the second degree when it is committed while defendant was engaged as a principal or an accomplice in the perpetration of a felony.