Everyone has the right to recline their seat, but please observe the following:
Not during meal service.
When starting to recline ensure there is nothing spillable on the tray behind.
Recline slowly, one notch at a time, as a signal to the person behind you that this is about to happen. Also look behind before you start.
Oh and one more thing, if you are getting out of your seat, do not grab the backrest of the seat in font of you. The guy in front (me) could be sleeping, just about to put a drink in his mouth etc.
Any kind of deliberate, constant banging on the backrest of the seat in front is not acceptable. This is especially directed to people with children.