BUT, I could be wrong.
From the Handbrake forums:

Windows GUI Usage Guide

First things first. Handbrake on the Windows Platform does NOT decrypt Commercial DVDs. Let me repeat this. It does NOT decrypt commercial DVDs.
Third-party software is required for this part of the process. (e.g. AnyDVD, DVD43 or DVD Decryptor)
(Note: Please note that these applications are not legal in many countries. You should consult the law in your own country before using these applications. We do not provide support for 3rd party applications!)