“You say we should not be concerned about but for causation because "We’re trying to ascertain what portion of the profits are attributable to the infringement, and how much to all the other inputs that there were." In the damages context we are trying to ascertain what portion of the harm (eg lost profits) are attributable to the tort (eg infringement), and we use but for causation there, at least in Canadian law. Why should we use a different basis for attribution in the accounting context? “

 

Because the justification for the obligation to pay damages for wrongdoing is not the same as the reason why there is a duty to account for profits for IP infringements.

 

If I commit a wrong, the reasons for the primary duty do not disappear, but generate a duty of next best compliance. This generates a duty that the plaintiff is put into the position he would have been in if the wrong had not occurred. This includes a duty to make good counterfactual harms that formed part of the reason for the justification for the original duty

 

This justification cannot (and does not) generate a (general) duty that all wrongdoers should be placed back in the position they would have been in if the wrong had not occurred (ie there is no general duty to account for profits from wrongdoing in the same way as there is a general duty to pay for damage caused by wrongdoing). The reasons for our duties in private law are (almost) never there to prevent other people from harmlessly making profits. Making profits that don’t harm others is, generally, a good thing.

 

Why then is an account of profits for IP rights (exceptionally) available?

 

Because in order to encourage the creation of novels, cures for covid, and phones that we know will work, we attribute the profits from copyright, patents and trademarks to the creators, inventors and manufacturers. But that attribution is inevitably a question of degree of contribution of the particular right to the actual profits made. Which isn’t a counterfactual question.

 

I agree that that enquiry then leads to a degree of uncertainty.