It’s a copyright law that includes anti-circumvention measures. Essentially, it makes it illegal to circumvent “technological protection measures,” including cell phone locks and protections against installing unapproved software on tablets like Apple’s iPad and Microsoft’s Surface RT (jailbreaking).
Technological protection measures are also found on eBooks, so breaking the DRM on an eBook to read it on another eReader is technically a crime, as well. (Not all eBooks have to contain DRM, however. Our eBook has no DRM, although it’s published through Amazon.)