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

_________________________________________________________