Summary

Historical importance of customary law.

Reasons for the recognition of customary law.

Requisites of a valid custom:

1. Reasonableness. 2. Opinio necessitatis. 3. Consistency with statute law. 4. Immemorial antiquity (unless general).

History of this rule.

5. Consistency with the common law (unless immemorial).

Conventional customs.

Theories of the operation of custom as a source of law:

1. Savigny’s—custom a formal source. 2. Austin’s—custom an historical source.

Relations between custom and prescription.