As more information is stored electronically, producing that information for the purposes of litigation creates challenges and perils for companies. In the U.S., new rules governing the retention and production of electronically stored information (“ESI”) went into effect in December, 2006, rules that impose obligations for record retention.
http://www.masslawblog.com/?p=122
http://www.enterprisestorageforum.com/continuity/features/article.php/3642421