One important difference between conventional crime and acts involving abuses of power is that many of the latter are committed under the guise of legitimacy. Concentration camps are justified by the need to protect internal security. Police abuse of power is legitimized as necessary to combat crime, to fight 'evil' with force. Extra-judicial executions are portrayed as acts of self-defence. The use of 'dirty tricks', undemocratic or outright illegal means, the overt or covert violations of civil liberties are thus rationalized and presented to an unsuspecting or an uninformed public as necessary and legitimate.