Customary law is a recognised source of law in Nigeria. For customary law to be applicable and enforceable by a Nigerian court, it must satisfy certain validity tests. Which of the following is NOT one of the established tests for the validity of customary law in Nigeria?

The validity tests for customary law in Nigeria, as codified in various Evidence Acts and court decisions, are the repugnancy test (not repugnant to natural justice, equity and good conscience), the incompatibility test (not incompatible with written law), and the public policy test (not contrary to public policy). The requirement that a custom must have existed since 1189 AD (time immemorial) is an English common law test for proving custom in England, not a Nigerian law requirement. Nigerian courts do not apply this specific date-based test; instead, they require proof that the custom exists and is observed by the relevant community.