Murder is the intentional, premeditated killing of another human being. The premeditation requirement for murder was historically described in the law as “malice aforethought.”

Laws regarding murder vary from state to state, and some states have a separate criminal offense of capital murder, which usually involves the most egregious circumstances, such as killing a peace officer in the line of duty or lying in wait to ambush and kill the victim. Capital murder offenses carry a potential death penalty.

And some states use the distinction of first degree murder (done with premeditation and punishable by death or life in prison) and second degree murder (generally an intentional killing without premeditation—also known as manslaughter or voluntary manslaughter in some states).

The criminal offense of murder is generally located in a state’s statutes—often in the penal or criminal code.

In Montana (MT), murder is classified under the state's penal code and is defined as the deliberate homicide of another person. The Montana Code Annotated (MCA) distinguishes between deliberate homicide (45-5-102 MCA), which is akin to first-degree murder, and mitigated deliberate homicide (45-5-103 MCA), which is similar to second-degree murder. Deliberate homicide involves the intentional and premeditated killing of another human being, reflecting the historical concept of 'malice aforethought.' Mitigated deliberate homicide occurs when the offender was under the influence of extreme mental or emotional stress for which there is reasonable explanation or excuse. Montana does not have a separate category for capital murder, but the state does have the death penalty as a possible sentence for certain cases of deliberate homicide. However, it's important to note that the application of the death penalty is subject to ongoing legal and legislative scrutiny. Manslaughter, which includes both voluntary and involuntary manslaughter, is addressed separately under 45-5-104 and 45-5-105 MCA, and involves the killing of another human being without premeditation.