Example: the killing by government agents of "civilians" on the grounds that they are suspected of being terrorists or of abetting terrorists, or, say, of being leaders of illicit drug cartels. Such killing is condemned by international law.
As defined in the US Torture Victim Protection Act of 1991, Section 3 (a): "A deliberated killing not authorized by a previous judgment pronounced by a regularly constituted court affording all the judicial guarantees which are recognized as indispensable by civilized peoples. Such term, however, does not include any such killing that, under international law, is lawfully carried out under the authority of a foreign nation."
A distinction is made between the killing of enemy soldiers, who, because they are combatants, are not considered entitled to due process, and the killing of people who are not declared combatants. Only the latter qualifies as "extrajudicial killing". This has led to considerable debate regarding specific instances of the killings of leaders of political groups.
Extrajudicial: done outside of a court's jurisdiction; not founded upon or dependent upon the authority of a court.
Note: In certain circumstances, an extra-legal execution is also an arbitrary execution.