From unwritten sources comes that law which use has sanctioned.

Explanation

The unwritten law — proved by long and uniform practice — is as binding as any statute, and in the common law tradition it is the more ancient authority.

Where this applies

• An unwritten legal tradition is challenged because it was never passed by a legislature.
• Someone argues that only written statutes can be law, ignoring customary rules.

See also

• 1.2.2 The general custom of the whole country is the common law of the country.
• 1.3.1 Custom is the best interpreter of the law.