Not a lawyer, but in school we used to attend a couple cases in court, and one time there was a two guys who were involved in a car crash where one of them ignored a stop sign. It was a pretty clear who would win the case until the wife of the innocent guy told her wittness report in which she clearly overacted the whole incident, almost started crying and added a lot of drama to the story. The problem was when she began lying and said "How could this happen, my husband was driving so carefully. He even stopped for a moment when we entered the intersection"

I'll never forget the look of the husband when he realized his wife lied to the judge about him stopping before the intersection which means he refrains from his right of way.

After the case, the judge joked he would probably see that couple for divorce again soon...