Section 116 (2) A plaintiff is not entitled by virtue of this section to any damages or to any other pecuniary remedy, other than costs, if it is established that, at the time of the conversion or detention:
(a) the defendant was not aware, and had no reasonable grounds for suspecting, that copyright subsisted in the work or other subject - matter to which the action relates;
(b) where the articles converted or detained were infringing copies--the defendant believed, and had reasonable grounds for believing, that they were not infringing copies; or
(c) where an article converted or detained was a device used or intended to be used for making articles--the defendant believed, and had reasonable grounds for believing, that the articles so made or intended to be made were not or would not be, as the case may be, infringing copies.
Does this not mean the opposite of your claim? It sounds to me that if you unwittingly bought a dodgy copy of something, the law thinks the copyright owner can get you to pay for a legit copy, but not punish you for your mistake.
In the specific case of the Harry Potter works, the fame might meet the threshold of reasonable grounds for believing, but noosphr's argument that "Up to 80% off all works that are in copyright terms are accidentally in the public domain" could grant a reasonable grounds for believing it is not.
This is one of those things that causes interesting court cases because a reasonable grounds for believing X is not the same thing as not reasonable grounds for believing not X.
Reasonable grounds for suspicion probably carries more weight here than reasonable grounds for the absence of suspicion, but cases have hung on things like this before , like the presence or absence of an Oxford comma.
