It's a gray area--the right to back up your media, and breaking the copy protection to do so. The latter, which is what DVDFab Blu-ray Copy does to make copies, is technically illegal according to the Digital Millennium Copyright Act. However, break and copy is what this program does, and does fairly well.
Blu-ray Copy is actually a module in Fengtao Software's $199 DVDFab All-in-One program. All the modules, which include DVD copying and video conversion, use the same interface, but you can only launch or use the ones that you've paid for. That can add up, as modules run $40 to $60.
DVDfab Blu-ray Copy worked relatively well for me, copying two titles fine, but halting halfway through Casino Royale. The program will make 1:1 copies, as well as compress moves to fit less capacious types of BD discs. The backups will play on systems without HDCP monitors or video cards. My only real complaint is that you need the separate $60 Blu-ray ripper module to save the movie to your hard drive in playable format.
The system requirements DVDFab quotes are ridiculously low. Unless you want your copying to take days per disc, a modern CPU and GPU are required. Also, an Internet connection is stated as a requirement. Whether this is for the program to gather keys for decryption or something else, I was unable to discover. DVDFab did not respond to PCWorld's email queries about this question.
If you want to make backups of your Blu-ray movies, DVDfab Blu-ray Copy will do it for you. However, there are cheaper programs that do the same thing, and even free ones such as the AVGo Media Recorder that will rip video, albeit not so conveniently.