--snipped from wiki--
In the United States, the law regarding murder varies by jurisdiction. In most U.S. jurisdictions there is a hierarchy of acts, known collectively as homicide, of which first degree murder and felony murder are the most serious, followed by second degree murder, followed by voluntary manslaughter and involuntary manslaughter which are less serious, and ending finally in justifiable homicide, which is not a crime at all. However, because there are at least 52 relevant jurisdictions, each with its own criminal code, this is a considerable simplification