Well, its not really a book about law in general...its a book about the law and steroids specifically. The same way a book about theft and the law is not a general law book.
The police get a tip you robbed a bank, they find cash matching numbers of dollars stolen from a bank buried on your property - you say you have no idea how it got there -anyone could have buried it there - but then they find a book titled "Robbing a bank and the law" in your house...hhhmmm.
You have a clean house - your computer is sanitized - a package from China mailed to your address is intercepted - you deny any knowledge of it, you say it must be some mistake and its not yours - but while the police interview you they spot a book about the legalities of steroids.....hmmmm.
Do I think the gov't can watch everything we order on a credit card --- YOU DON"T ? ! They can know every book you check out of the library -