If someone buys a CD, they can do pretty much what they want with it, loan it out, sell it, swap it, use it for a Frisbee, I guess the same thing applies to books. But one thing you can't do legally is copy it. If they copy it and give or sell or swap the original, they are suppose to destroy any copies they made. I doubt that they do that though. It seems most people have as much respect for the copyright law, as a tomcat has for a marriage license.