The second element of the test, opinio juris, the belief of a party that a particular action is required by the law is referred to as the subjective element. The ICJ has stated in dictum in North Sea Continental Shelf that, "Not only must the acts concerned amount to a settled practice, but they must also be such, or be carried out in such a way, as to be evidence of a belief that this practice is rendered obligatory by the existence of a rule of law requiring it".
The second element of the test, opinio juris, concerns a party's conviction that an action is required by law. The ICJ has indicated in dictum regarding the North Sea Continental Shelf: "Not only should the actions involved be part of a consistent pattern, but they must also show a belief that this practice is legally binding."