During jury selection the judge will ask if you deliver a guilty verdict if the defendant is guilty. When you say no, you're off the jury.
If you lie the judge will kick you off the jury when he figures out you're lying. He'll be angry, and he can fine or jail you if he wants to make a point.
A judge can absolutely jail you for contempt of court. And he pretty much gets to decide what that means. It's unlikely you'd get jailed for this kind of thing, but it's not impossible.
If you lie the judge will kick you off the jury when he figures out you're lying. He'll be angry, and he can fine or jail you if he wants to make a point.