It is illegal to bypass DRM protection measures to make your backup.
Circumvention means avoiding, bypassing, removing, deactivating or impairing a technological measure without permission from the copyright owner. This includes bypassing iTunes DRM to copy the music files you bought or using software to break DRM locks to copy DVDs.
HOWEVER...
Prior to DRM and the DMCA, you could make backup copies of your legally purchased CDs and DVDs so you could play them at home, at work, in the car or on portable devices, or to store backup copies.
This copying was not necessarily legal; in fact, the law has never been clear on the legality of copying copyrighted material for personal use. Making backup copies of digital works that you legitimately owned for private, noncommercial use was, however, considered a fairly acceptable practice -- certainly widespread -- and DRM did not exist to stop you.
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Now all that mumbo jumbo aside what you can do if you are concerned the copyright police will come to your door and take you away is (I do not condone breaking any laws) ...
When you buy DvD's today, many of them have the ability to be stored/retrieved and or subscribed on the internet for retrieval later/by other devices. Disney for example has this feature as well as there are other subscription services that offer this.
Be aware that this is ONLY for DvD's you've purchased with this feature not for DvD's you may have purchased prior.