First degree murder is defined by federal and state laws, which vary by state, but generally define it as a killing which is deliberate and premeditated. Many states define first degree murder as a killing committed in connection with felonies such as rape, burglary, arson, or involving multiple deaths, the killing of certain types of people (such as a child or a police officer), or certain weapons, particularly a gun. It is distinguished from second degree murder, which usually does not require premeditation, and from manslaughter, which lacks premeditation and suggests that at most there was intent to harm rather than to kill.
Under federal law, the government must prove each of the following elements beyond a reasonable doubt:
To kill with malice aforethought means to kill either deliberately and intentionally or recklessly with extreme disregard for human life.
Premeditation means with planning or deliberation. The amount of time needed for premeditation of a killing depends on the person and the circumstances. It must be long enough, after forming the intent to kill, for the killer to have been fully conscious of the intent and to have considered the killing.