Optimal legal standards for competition policy further re-visited

Katsoulacosand Ulph (2009) showed how all the factors identified as being relevant to choosing between a Per Se and an Effects-Basedlegal standard in terms of their decision error costs could be combined into asimple formula for determining which standard to use. Seifert (2020) gives an alternativecharacterisation of an Effects-Based legal standard and shows that itsdecision error costs are never higher than those of Per Se. We argue that nevertheless our originalformula remains valid for choosing between these two legal standards.