goretsky: It is not legal to make archival (backup) copies of DVDs encrypted with CSS in the United States, even for personal use. The DMCA specifically took the long-held right to do this away from Americans when it was enacted. There are some people who state that the Audio Home Recording Act of 1992 could be construed to covering DVDs with respect to "home use" copying. If the Fair Use Act of 2007 passes, this may change in the U.S., however, for the time this should be considered the answer to that particular question in this forum.
LockerGnome
John Wilkinson: In the US the primary law cited in such cases is the DMCA, which forbids the circumvention of copy protection mechanisms except in extremely narrow exceptions that do not apply to the average individual. Some will argue Free Use gives you the right to do what you wish with the content since you purchased it, but at this time there is no such legal exception. Thus, despite their prevalence we cannot discuss the tools used to decrypt DVDs as it is technically illegal.
CNET
?(G) The prohibition contained in subparagraph (A) shall not apply to–
`(i) an act of circumvention that is carried out solely for the purpose of making a compilation of portions of audiovisual works in the collection of a library or archives for educational use in a classroom by an instructor;
`(ii) an act of circumvention that is carried out solely for the purpose of enabling a person to skip past or to avoid commercial or personally objectionable content in an audiovisual work;
`(iii) an act of circumvention that is carried out solely for the purpose of enabling a person to transmit a work over a home or personal network, except that this exemption does not apply to the circumvention of a technological measure to the extent that it prevents uploading of the work to the Internet for mass, indiscriminate redistribution;