That which is valid in law has legal strength, force, and effect, or incapable of being rightfully overthrown or set aside.

Explanation

(English-origin maxim — no Latin equivalent; the English title is the original form.) A valid instrument carries the full force of law and cannot be collaterally attacked; opposing parties must show a jurisdictional or constitutional defect to overcome it.

Where this applies

• A valid legal instrument is collaterally attacked by a party who had no standing.
• A properly executed contract carries the full force of law and cannot be set aside on a whim.