Dat feel when your parents tells you to not do something, but you end up doing it, and when they are mad at you.... you cry, say sorry, and that you won't do it again. Somehow, they end up forgiving you....
In my pure and solely opinion, the "No exception" rule should'be enforced. Consequences need to be made clear so the person can know what is going on if he does that. Now some people really deserves "Second chances", but the majority of they doesn't , and that made me reach the conclusion that it doesn't wort to risk on it.
Forget your son once... most likely, he will do it again.