If I own the physical copy of a book is it illegal to torrent the ebook version?

Asked by joshisradd (238) February 6th, 2010 from iPhone

The questions says it pretty well; I have a lot of books that I would like to read again on my nook but hate to purchase them again when they are siting on my bookshelf. I’m not very well versed in all the copyright laws but I know if you own say a cd or DVD you can have a digital backup if you don’t distribute it, but I have no idea if books live under the same rules.