Custom is to be construed strictly.

Explanation

A custom that departs from the general law must be proved precisely as alleged — it will not be extended by inference to cover cases not clearly within its terms.

Where this applies

• Someone tries to stretch a local custom beyond the specific situations it covers.
• A party argues that a custom applying to one type of transaction should apply to a completely different one.

See also

• 1.2.4 Things derogatory to the common law are strictly interpreted.
• 1.3.3 A custom must be certain, for an uncertain custom is held as nothing.