A custom of the truest antiquity is to be retained.

Explanation

(English-origin maxim.) A custom of proven antiquity should be preserved and enforced — use this to defend a longstanding practice against legislative or administrative attempts to abolish it.

Where this applies

• A legislature attempts to abolish the common-law right of self-defense, but the court preserves it because it is a custom of the truest antiquity traceable to time immemorial.
• A city tries to eliminate the ancient practice of public access to navigable waterways, but the court holds that such a deeply rooted custom must be retained.
• An agency attempts to remove the longstanding right to a hearing before property deprivation, but the court finds the custom too ancient and fundamental to discard.