They said “specific” book, which I take to mean “we found this book at a crime scene, can you tell us who checked it out?” Not, “I want to know everyone who checked out war and peace this year.”

But after thinking about it, I think they meant the former and you meant the latter. But to the library, it’s the exact same thing. A library doesn’t (traditionally) track each and every book, so if it’s a popular book, it could have been checked out by any number of people.

I think this is fine, as long as courts work to keep the scope small and laws allow people to do whatever they want without hindering freedom.