Opinio juris 是指法律确信，是拉丁文opinio juris sive necessitatis（法律必要确信）的缩写；a conviction that the rule is obligation 确信（体现于惯例中的）规则是法律上有拘束力的。

英文释义如下：

Opinio juris is a Latin phrase that means "an opinion of law or necessity." In international law, it refers to the subjective obligation of a state to follow a particular law. It is the second element necessary to establish a legally binding custom. The International Court of Justice requires that the custom must be "accepted as law." However, the concept of opinio juris is still debated in international law.

具体使用场景可参考如下双语例句：

The practice must comply with the “ opinio juris"requirement ( short for the Latin opinio juris sive necessitatis — a conviction that the rule is obligatory) to transform it into customary international law.

实践必须符合“法律确信”要求（拉丁文 opinio juris sive necessitatis 的缩写——确信该规则是强制性的），才能将其转化为习惯国际法。

Relationship between the two elements: State practice and opinio juris sive necessitatis, and their respective roles in the identification of customary international law.

“国家实践事例”和“法律意见或履行法律义务之行为”两个因素之间的关系及各自对于习惯国际法之确定的作用。

Some thought should be given to whether draft articles D1 to J1 adequately reflected the practice and opinio juris of countries from different regions and of States especially affected by expulsion.

第D1到J1 条草案是否充分反映了不同区域国家以及特别受驱逐问题影响国家的实践和法律确信，对此应作出思考。