Dusty Phrases

Hi! Welcome to “Dusty Phrases.” You will find below an ancient phrase in one language or another, along with its English translation. You may also find the power to inspire your friends or provoke dread among your enemies.

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Falsus in uno, falsus in omnibus


False in one thing, false in everything

This is a legal maxim which states that a witness who has testified falsely about one thing cannot be considered credible concerning anything else. From Wiki:

Falsus in uno, falsus in omnibus is a Latin maxim meaning “false in one thing, false in everything”. At common law, it is the legal principle that a witness who testifies falsely about one matter is not credible to testify about any matter. Although many common law jurisdictions have rejected a categorical application of the rule, the doctrine has survived in some American courts.

The origins of the doctrine of falsus in uno, falsus in omnibus in the common law have been traced as far back as the Stuart Treason Trials in the late seventeenth century. However, the widespread acceptance of the principle in seventeenth century English courts suggests that the doctrine has much earlier roots. In the seventeenth and eighteenth centuries, the principle functioned as a mandatory presumption that a witness was unreliable if they previously lied while offering testimony. By the early nineteenth century, English courts began instructing juries that they may presume a witness who testified falsely was unreliable, but such a presumption was not mandatory. In 1809, Lord Ellenborough rejected a categorical application of the rule, stating that “though a person may be proved on his own shewing, or by other evidence, to have foresworn himself as to a particular fact; it does not follow that he can never afterwards feel the obligation of an oath.” Although some American courts disfavor the mandatory application of the doctrine, others continue to uphold a mandatory presumption of unreliability for witnesses that have previously testified falsely.