Murder is the act of criminal homicide. Of the six grades of homicide, only three are crimes, and only two are classified as criminal homicide, or murder. The six grades of homicide are: justifiable homicide, such as self-defense or capital punishment; excusable homicide, such as accidents or cases of insanity; first-degree criminal homicide, or murder; second-degree criminal homicide, which is also murder; voluntary manslaughter; and involuntary manslaughter. First-degree murder is purposeful and is defined as premeditated, deliberate, or malicious. Murders committed in connection with a felony are also categorized as first-degree murder. Second-degree murder covers homicides committed in the heat of passion or through malicious intent. In both first-degree and second-degree murder, the intent to harm is present. Homicides that are committed as a result of sudden passion or by accident are generally classified as either voluntary or involuntary manslaughter. In 12 states, the maximum penalty for murder is life-imprisonment; in the remaining 38 states, the maximum penalty for murder is death by execution, although each of these states has a minimum age limitation on the death penalty. The federal government allows the death penalty for murder.