L.M.
Personally, I would not back off. I think he needs to know you are serious and consistent. If that isn't working, you need to come down harder. That said, I think you need to also sit and listen. Let him talk (if he will) and if he won't he at least will get the message you are willing to listen to him. I also think it is important to define just what he needs to do to get the privileges back. All 14 year olds are going to think you are being unreasonable but it is the long term message that will count. I would also look at how many activities, sports ect.. he is doing. It is so hard to for them to get enough sleep and that impacts how well they can focus and get assignments done. BTW, I have a 14 yr old boy, too~