By definition, murder is the unlawful killing of another human being with malice aforethought. Usually murder can be distinguished from other methods of homicide by these elements of malice and the lack of lawful justification. All jurisdictions view murder as an extremely serious crime and because of that they impose severe penalties on those who commit it.

Malice aforethought does not necessarily mean premeditation. An intent to kill, intent to cause serious bodily harm short of death, reckless indifference to a high risk to human life, and intent to commit a dangerous felony are all states of mind that are recognized as malice aforethought. Under the intent to kill state of mind, if a criminal purposely uses a deadly weapon, such as a gun or a knife, on a victim, this authorizes the inference of intent to kill.

As with the majority of legalese, the exact definition of murder varies from jurisdiction to jurisdiction and is generally codified in some form of legislation. Some jurisdictions consider murder as a common law crime and are viewed as so wrong that there’s no need for any legislation to define it. In these jurisdictions, the previous decisions made by the courts in precedent case law are used to define what is considered to be murder.

There are some exceptions to the rule, such as unlawful killings without malice or intent, justifiable homicide, suicide, capital punishment, and the killing of enemy combatants by lawful combatants during war.

It is a requirement that the victim of murder be a human being who was still alive at the time of the murder. Most jurisdictions consider the killing of a fetus or unborn child as a different type of crime. They consider a child as someone who could survive if it had been born, while a fetus couldn’t.

There are also some mitigating circumstances that may affect the state of mind of the defendant at the time of the murder that may change the charges against them. A person might be found guilty of manslaughter on the idea of diminished responsibility instead of murder if the defendant can prove that they were suffering from a condition that can affect their judgment at the time of the incident, such as depression, negative side effects from medication, and post traumatic stress disorder. The courts take all of the above into account when determining if a defendant should be charged with murder or a slightly lesser charge, such as manslaughter.