Murder

Murder (also called intentional homicide) is when one person unlawfully kills another. It is one of the most serious crimes under the laws of most countries and typically carries the harshest penalties in criminal justice systems.

Legal systems distinguish murder from other forms of unlawful killing, such as manslaughter (killing without intent) and deaths resulting from negligence. The distinction turns first on the perpetrator's state of mind: was there intent to kill or to cause serious injury?

Elements of the crime

Most legal systems require two things. One is the act itself—the killing—and the other is a guilty mind or intent. When both are proved, the crime is classified as murder. If intent is absent but gross negligence is present, the crime falls into a different category with lighter penalties.

Degrees and aggravating circumstances

Many countries divide murder into degrees. The first degree typically covers killing that was premeditated or committed with deliberate cruelty. Other degrees cover killings that were unplanned. Aggravating circumstances for sentencing include the victim being a state official, the killing occurring during another crime, or multiple deaths.

Defences and mitigation

Common defences include self-defence, when a person wards off immediate danger to their own life, and mental conditions that prevented the perpetrator from understanding their actions. Sudden provocation stemming from intense emotional distress can also lead some legal systems to reduce murder to a lesser form of homicide.

Punishment

Penalties for murder vary by country. They range from lengthy imprisonment to life imprisonment to, in jurisdictions that retain it, execution. Many countries have abolished capital punishment or replaced it with life sentences.