Is independent creation a defense to copyright infringement?

Independent creation is where two separate people both create the same work, or works that are substantially similar, on their own and independent of each other. In patent law, independent creation does not matter - ultimately, only one inventor will be entitle to patent protection. In copyright law, however, independent creation does matter and can be a valid defense to a claim of copyright infringement. For example, if you wrote a book and were sued for copyright infringement of another book, and you could successfully show that you came up with the book on your own and it is simply a coincidence that both books have similar plot developments, characters, language, etc., you would not be guilty of copyright infringement and your work would be entitled to its own protection.