One of the things God hates is a lying witness (Prov 6:16-19). Hates. But what happens when someone gets on the witness stand and lies? What does God have to say about that? Because it happens.
First, they must make a “careful investigation” (Deut 19:18). If it is found that “if the witness turns out to be a liar who has falsely accused his brother, you must do to him as he intended to do to his brother” (v. 18-19).
Understand that if a witness testified against someone, they had to be the person to bring the judgment as brought by the judge. For example, if a person was to be killed for their crime per the judge’s ruling, the witnesses had to be the people who did the execution.
This amped up the importance of an honest witness. Because if they were going to testify to someone committing a crime, then they better be sure because they were going to have to face the responsibility in bringing that judgment to reality.
But if a witness lied on the witness stand? For Israel, a lying witness was to receive the crime that he false accused of his brother.
That’s how much God hates false witnesses.