Perjury is the criminal offense of knowingly making a false statement under oath about a material fact. Not every falsehood offered as testimony under oath is perjury. Perjury has three motivations:
- To escape punishment
- To cause injury
- To express contempt of court
Conscious perjury is a sin.
See Exodus 20:16 with multiple commentaries "Thou shalt not bear false witness against thy neighbor."
Compare John 8:44 with multiple commentaries "The father of lies".