Ordinary common sense and consideration seem to be what is required, and what everyone here is recommending. On some planes that have trays in the arms it is impossible to get a tray out when the seat in front is reclined more than an inch.

There is hardly any instance where reclining as far as the seat goes is not a serious inconvenience to the person sitting behind. Therefore, it shouldn't be done. And when it is done, I think we shouldn't hesitate to point out the inconvenience.