Home › Topics › Arms & Self-Defense Topic Arms & Self-Defense 2 maxims cross-cutting the 12 books 2.5.1 The right of arms is necessary where laws are deficient. Jus armorum est necessarium ubi deficiunt leges. Source: Common law maxim; cf. 2 Inst. 574 When the law fails to protect the citizen, the citizen retains the natural right to protect himself. The right of arms is the last safeguard of all other rights. 2.5.2 The laws permit the taking up of arms against the armed. Arma in armatos sumere jura sinunt. Source: 2 Inst. 574; Broom, Max. 26; Weisman, 9a The right to bear arms includes the right to use them in defense against armed aggression — whether from private actors or tyrannical government.