Falsus in uno, falsus in omnibus is a Latin phrase meaning “false in one thing, false in everything.”[2] 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.[3]Although many common law jurisdictions have rejected a categorical application of the rule, the doctrine has survived in some American courts.[4]
https://en.m.wikipedia.org/wiki/Falsus_in_uno,_falsus_in_omnibus
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