and how often is it enforced?
The background is this. I just finished serving as a juror on a minor criminal case. One of the witnesses for the prosecution was a friend of the defendant. He told a relatively unbelievable story, more in support of the defense. After he testified, an assistant DA was called, who said that during the pre-testimony interview this guy changed his story four times, ending with one different from his testimony in court. The defendant then testified in line with the now discredited testimony of this witness. The prosecutor said that the defendant and this witness spoke together that morning.
This guy was clearly lying, and both the prosecution and defense basically said so in their closing statements.
My question: what penalty was this guy subject to? How often is it used. I suspect the penalty is greater than that for the defendant in this case (we found him guilty.) How often do witnesses lie, and how often is anything done about it?