False in one thing, false in all things.

Explanation

Where a witness is shown to have testified falsely on a material point — one on which he could not be presumed to be mistaken — the tribunal may reject the whole of his testimony.

Where this applies

• A witness lied about one important detail so I want their entire testimony thrown out.
• The other side's key witness got caught fabricating part of their story.
• An expert witness was proven wrong on a major point so how can the rest of their testimony be trusted.

See also

• 9.1.5 No one ought to be a witness in his own cause.
• 9.2.3 An oath is indivisible; it cannot be held partly true and partly false.