Let me say at the outset that I am very pleased to comment on this paper. It deals with an important issue in a thoughtful and thought-provoking way. Having said that, I believe that it is seriously flawed. My purpose here is to set those flaws out. In essence, the paper proposes that s36 be modified through an “effects test” – that is, a test that assesses whether the conduct alleged to be in breach will have the effect or likely effect of substantially lessening competition. The authors recognise that it is not easy to define or identify anti-competitive effects. They also acknowledge that there is a concern that the resulting uncertainty might deter firms from engaging in actions that while they harm competitors do not harm competition. So as to address these concerns, the authors propose that the effects test be given a particular definition, set out at some length in their paper.