Opinio Juris

Opinio juris is a Latin term used in international law to describe the belief or sense that a particular legal rule is a legally obligatory practice, not just a habit or tradition. In simple terms, it’s the mindset of states or parties that their actions are carried out because they consider it a legal duty, not merely out of convenience or custom. This belief helps distinguish true legal obligations from informal habits, showing that the practice is followed because it’s seen as legally required, which is essential for establishing customary international law.