To Act or Not To Act?

While taking a written examination, you see another student cheating. You have no doubt about the student's behavior. Your experience is that people don't get punished for that behavior. You feel the faculty should do a better job of preventing and punishing such behavior. You don't think your dental school ethics committee is effective. The knowledge upsets you and causes you to distrust your other classmates. In this instance the faculty proctors don't seem to notice. If you called it to their attention, the student would be caught in the act.

What should you do? What would you do?