Suppose I wish to use copyrighted printed materials under fair use, and let's assume for the sake of argument that it is completely obvious that my usage correctly falls under fair use guidelines.
As far as I can tell, fair use says nothing one way or another about where the content comes from. Could I, for example, duplicate portions of illegally distributed versions of the material available online if my own usage of it is legitimate under fair use? Or is it the case that fair use is only legitimate if my source is a legally distributed one?