But there was one comment in the review that jarred with me at the time, and after thinking about it for a while, I've figured out why.
It came in the bit on p29 where MBIE was talking about how the way s36 works in the courts stacks up against the criterion of 'simplicity'. They were right to say, not well, in particular from the point of view of a plaintiff (typically the Commerce Commission, but firms can also have a go at private prosecutions). When the courts decamp into the alternative universe of the 'counterfactual' - what would firms have done in a hypothetical world where they didn't have market power - the possibilities for rabbits to run in every direction are endless. MBIE was right to call the process "defendant friendly".
But along the way MBIE said this (I've added the bit in brackets to make MBIE's point clearer):
Frankly, the first sentence is just plain wrong (the second is mostly right).The problem here is not so much one of predictability for powerful firms – businesses will generally know if they are acting in a way that they would not in a competitive market. The problem seems instead to be the cost and delay involved in [the plaintiff] making a case under the counterfactual test
Businesses very often won't know if they are acting in a way that they would not in a competitive market. That's precisely why we, and the Aussies, and competition authorities globally, have been having these rethinks about defining abuse of market power and policing it: it's a grey area, where reasonable people can come to different conclusions. What is vigorous but fair competition by a big company can be very hard to tell from tactics that exploit the company's bigness to skew the competitive playing field. In fact, that's exactly what the (in)famous Pink Batts case (which MBIE cites) demonstrated: courts took different views, with the House of Lords, who had the last bite of the cherry, taking the vigorous but fair line.
The biggest current example is Google's bunfight with the EU competition police. Is it really abundantly clear that Google's giving higher rankings in search results to companies that advertise with it is "anti-competitive"? If you, um, google it, you'll readily find experts on both sides.
I wasn't born yesterday: of course, there will be instances where there are guys in black hats who know they are wearing them. There have been clear cases where competition authorities have spotted and pinged egregious behaviour that would have been found anti-competitive on pretty much any reasonable definition of abuse of market power.
But it's not the right way to typify where many companies are likely to find themselves - in the real, greyer world.