The DMCA circumvention of DRM copy protection issue creates somewhat of a conundrum concerning making personal copies of DVD movies. Ironic, as key representatives of the music and movie industries, even members of Congress, have apparently indicated it legal to make backup copies of purchased CDs and DVDs. However, the sticking point is the DMCA circumvention provision considering CSS is used in most all commercial DVDs. So not legal except in a few cases related to academic uses.
If that's not enough of a quagmire, the Copyright Office in its
triennial review of exceptions published not too long ago, rejected "ripping" as being fair use as it involves space shifting. By transferring a DVD to hard drive, or converting to a format playable by a mobile device.
Manufacturing or distributing software that circumvents CSS is also technically not legal, though makers of these apps typically get around this by placing their operations overseas. However, it is apparently not illegal to personally own or use such apps. Especially, since they would be necessary for use in situations where DMCA exemptions would apply.