Abstract
A strong moral reason for prohibiting doping in sport is to be found in the bad choices that would be faced by clean athletes in a sporting world that tolerated doping. The case against doping is not, however, to be grounded in the concept of coercion. Instead, it is grounded in a general duty of sport to afford fair opportunity to the goods that are distinctively within sport's sphere of control. The moral reason to prohibit doping need not be balanced against any autonomy claim of athletes who would prefer to dope because, upon closer examination, such claims have no force. The moral reason to prohibit doping does, however, need to be balanced against the enforcement costs imposed on all athletes by effective prohibition.