Before the famous case of Furman v. Georgia in 1972, most states distinguished two degrees of murder...
After the Supreme Court placed new requirements on the imposition of the death penalty, most states adopted one of two schemes. In both, third degree murder became the catch-all, while first degree murder was split. The difference was whether some or all first degree murders should be eligible for the most serious penalty (generally death, but sometimes life in prison without the possibility of parole).
The first scheme, used by Pennsylvania and the most common among other states:
1. First Degree Murder: An intentional killing by means of poison, or by lying in wait, or by any other kind of willful, deliberate and premeditated action.
2. Second Degree Murder: Homicide committed by an individual engaged as a principal or an accomplice in the perpetration of a felony.
3. Third Degree Murder: Any other murder (e.g. when the intent was not to kill, but to harm the victim).
The second scheme, used by New York among other states:
1. First Degree Murder: Murder involving special circumstances, such as murder of a police officer, judge, fireman or witness to a crime; multiple murders; and torture or especially heinous murders. Note that a "regular" premeditated murder, absent such special circumstances, is not a first-degree murder; murders by poison or "lying in wait" are not per se first-degree murders. First degree murder is pre-meditated.[5] However, the New York Court of Appeals struck down the death penalty as unconstitutional in the case of People v. LaValle, because of the statute's direction on how the jury was to be instructed in case of deadlock in the penalty phase.
2. Second Degree Murder: Any premeditated murder or felony murder that does not involve special circumstances.[6] [emphasis added]