A custom is an embodiment of a principle of utility or justice that has commended itself. A custom may be relied upon as a source of law in the determination of certain civil disputes.
However, not every custom is applicable as law. For a custom to be relied upon as a source of law, it must: exhibit certain qualities:
- Reasonableness: a good local custom must be reasonable. It must be consistent with the principle of justice.
- Conformity with written law: a local custom must be consistent with statute law. This is because parliament is the Supreme Law making body and has authority to render a rule of custom inoperable.
- Observance as of right: a good local custom is that which a community has observed openly and as of right, that is to say not force or stealth, nor at will.
- Immemorial antiquity: the local custom must have been observed since time immemorial. Time immemorial means that no living person can attest as to when the custom did not exist.
- Civil cases: a local custom can only be relied upon a court of law in the resolution of civil disputes.
- Subject to or affected by: for a rule of custom to be relied upon as law one or more of the parties must be subject to it or affected it.
- Repugnance to justice and morality: a custom will only be relied upon a court of law if it is not repugnant to justice and morality.
- Proof: the party urging the court to rely on a particular rule of custom must prove evidence, unless the custom is a matter of public notoriety.