Last month, my minor son was questioned by the police. I was there during the questioning. The officer who did the questioning has now lied in court about my son's answers, and the whole thing has become a nightmare. Since the questioning was not taped, so I can't prove the officer lied. Are there any laws about using questioning that was not taped?

Yes. The same as if it was taped. The office can testify and so can your son.