A wilful killing is a killing that is premeditated; it occurs as the result of a deliberate plan being made and carried out. In wilful killings, the killer has plenty of opportunities to change his or her mind, but still goes through with it. Wilful killings can be punished more severely than other types of killings that do not involve premeditation.
An example of a wilful killing would be a person who plans to murder someone, who goes and buys a gun, puts a plan in motion to kill the person, and then carries out the plan. This would be different from a killing in which a person lost control in the heat of the moment; for example, if a man killed his wife's lover after finding them in bed together. Wilful killing can also refer to the killing of a person who was protected under the Geneva Convention of 1949 by a person who had knowledge of the victim's protected status.