I have recently purchased some "used" books via amazon.com
Oddly enough, they come with library identifications on them, some have indicated they are withdrawn but others do not indicated they are discarded. Are they "lifted"? I have no evidence. I see this Ask MeFi article: How do I know if former library books for sale are really former library books? which suggests this is common and some libraries are just lax in labeling books as discarded. So I will assume it is legal, though doubts remain.
Now, I know it is illegal to upload scanned books that are still under copyright if they are not your own, but lots of books can obviously be found online at various places. While searching the internet, I discovered a Russian pirate copy library site, no longer up: http://gen.lib.rus.ec/ which had lots of books available for download, including The Transportation Experience, which I wrote with Bill Garrison.
Two points come to mind:
(1) Hey, cool, my work is worth pirating.
(2) Is it illegal *for me* to download this? (It is probably illegal for you to download it, (unless you are my coauthor) but the real crime would be if you uploaded it). It is obviously not immoral to download a book I wrote and have copies of, even if I did license Oxford University Press to publish it. I.e. could I be prosecuted for downloading a copy of my own work?