There are some things which are not proper though lawful; but certainly those things are not proper which are not lawful.

Explanation

(English-origin maxim.) Something may be technically lawful yet still improper — but what is unlawful can never be proper, and courts will not enforce an act that is both unlawful and improper.

Where this applies

• A government action that was unconstitutional from the start is defended because years have passed.
• A void judgment is enforced decades later and someone challenges it as still void.