There has been some discussion and disagreement in the past on the nature of the rule of local remedies, as such, or its formal character. The issue has generally been formulated in terms of whether the rule is one of substance or procedure. Sometimes the discussion has been centred more specifically on when the ‘responsibility’ at international law of the respondent state arises, which may or may not be the identical question involved in the consideration of the nature of the rule as one of substance or procedure depending on how the terms used are defined.

It has also been stated that the differences of opinion, found also in state practice and judicial statements, are ‘of theoretical rather than practical interest’. As will be seen, while this may to a large extent be a plausible assessment, there are certain matters which could in practice be affected by the view taken of the nature of the rule. On the other hand, it is necessary to define what exactly the discussion is about, as often some of the disagreement may appear to stem from a confusion about what are the parameters of the subject, while it has to be acknowledged that there is some genuine difference of opinion on substantive matters connected with the formal character of the rule.