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 Washington State, murder is classified into degrees, with first-degree murder being the most serious form of homicide. According to RCW 9A.32.030, first-degree murder involves a premeditated intent to cause the death of another person, which aligns with the historical concept of 'malice aforethought.' First-degree murder can also occur under certain other circumstances, such as during the commission of a serious felony. Second-degree murder, as per RCW 9A.32.050, generally involves intentional killing that is not premeditated, which is akin to what some jurisdictions may refer to as voluntary manslaughter. Washington does not have a separate category for capital murder, but it does have aggravating factors that can lead to harsher sentences, including life imprisonment without parole. However, as of the knowledge cutoff in 2023, Washington State has abolished the death penalty, so it is no longer a sentencing option for first-degree murder or any other crime.