At a political trial I once went to watch, I saw a cop lie on the witness stand, after having also lied on a police report. He lied very blatantly, over and over again, and experienced no repercussions, though the judge did start to seem mildly annoyed after a while. Later I met up with a defense attorney I have known since childhood, and told him I had seen a cop lie on the witness stand. He told me that around here that is pretty much standard procedure.