Criminal possession of a weapon is the unlawful possession of a weapon by an individual. Many societies both past and present have placed restrictions on what forms of weaponry private citizens (and to a lesser extent police) are allowed to purchase, own, and carry in public. Such crimes are public order crimes and are considered mala prohibita, in that the possession of a weapon in and of itself is not evil. Rather, the potential for use in acts of unlawful violence creates a perceived need to control them. Some restrictions are strict liability, whereas others require some element of intent to use the weapon for an illegal purpose. Some regulations allow a citizen to obtain a permit or other authorization to possess the weapon under certain circumstances. Lawful uses of weapons by civilians commonly include hunting, sport, collection and self-preservation.