Inadimplenti non est adimplendum - "One has no need to respect his obligation if the counter-party has not respected his own." This is used in civil law to briefly indicate a principle (adopted in some systems) referred to as the synallagmatic contract.[3]⏎
Fiat justitia et pereat mundus - "Let there be justice, though the world perish." Often used as a motto, notably by Ferdinand I, Holy Roman Emperor.⏎
Iura novit curia - The judge knows the law (technically, there is no need to "explain the law" or the legal system to a judge/justice in any given petition).⏎