The issue of pirated books is a common one im Latin American countries. Diego Ariel Vega wrote  [es] about it on Infotecarios, and pointed out that the traditional response when such books are confiscated is to burn them, but he raises some questions:
Who should be responiable for that decision? Government authorities, publishers, authors? Are we considering the rights, opinions and decision of the affected people? Is there appropriate legislation? Is there consensum or coincidence when addressing these cases in region? Is really the destruction a solution to be considered? In my opinion, the choice of destroying books, as pirated as they might be (Never throw a book away! is a recommendation by UNESCO), it's something that annoys me, it makes me think of unpleasant images and it just doesn't seem to close down.
And then he adds:
Well, once we come across illegal material that meets some basic quality and content requirements, other questions appear: is this material suitable for libraries and other institutions? Or for non lucrative options such as “Free books”, “Bookcrossing” , etc. with explanatory stamps to use and raise awareness? Can't they be used, for instance, as donations for rural, low-income libraries, etc.? Can't they be reused to educate and be an example of the situation, explainig differences?
The debate is open.