Precedents that pass sub silentio are of little or no authority.

Explanation

(English-origin maxim.) A prior decision that did not actually consider or address the point in question carries no weight as precedent on that point — authority requires deliberate adjudication.

Where this applies

• The old case is being cited as precedent but it never actually addressed the issue at hand.
• A prior decision that didn't consider this point can't serve as authority for it.