An outlaw is a person living outside the law.
The welfare and the existence of a community against outside world and its enemies depended on the maintenance of the peace that is safeguarded by custom and reason. The one who broke the peace had no more place within the community which he had imperilled and polluted. He had to be slain or expelled. Outlaw was totally expelled from human society and treated like an animal. Thus, in its earlier forms outlawry included all punishments in one.
Outlaws are fugitives from the law. Turning them into romantic anti-heroes standing up to the social and psychological oppression of the establishment through the myths of Bonnie and Clyde, Robin Hood and Jessie James or into evil non-humans through the over-responses of Western governments and news-media has, to a large degree, given certain types of crime legitimacy. One man's terrorist is another's freedom fighter. Indiscriminate killing, while not acceptable, is understandable. When outlaws are seen as people who are criminals, outside the law, anti-social and brutal misfits, society will find a way of progressing toward effective responses to their dangerous activities.