In politics, authority (Latin auctoritas, used in Roman law as opposed to potestas and imperium) is often used interchangeably with the term "power". However, their meanings differ. "Power" refers to the ability to achieve certain ends, 'authority' refers to the legitimacy, justification and right to exercise that power. For example whilst a mob has the power to punish a criminal, such as through lynching, only the courts have the authority to order capital punishment.