I don't have the exact numbers here, but, roughly 43 states allow hunting deer with a rifle. Of those 43, I believe 38 allow the use of .22 Centerfires. The argument is NOT whether the cartridge is ethical. The mere fact that the vast majority of states allows it, to me, means that the cartridge is an ethical choice. Thus, the "ethics" question becomes whether the hunter, when using a legal caliber, is sufficiently selective of his target and adequately restricts the distance at which he takes his shot.