[anoonmoose]

The example you described is handled by our current system. (For the moment, let's put aside whether or not the system always works as intended). Evidence isn't just "brought to court by someone else". It doesn't just appear. Someone needs to be saying "this is the accused saying this"- during the discovery process before the trial the defense will have an opportunity to refute that claim. If it's another witness, they will be cross-examined by the defense and the jury will need to decide if the testimony is credible or not. If they lie, they will have committed perjury, and all of what I just said is true (roughly, I'm not a lawyer) whether you use AI or a good voice actor.