The short version being the 'Sonny Bono Copyright Term Extension Act' of 1998 is pejoratively referred to as the 'Mickey Mouse Protection Act'.
http://en.wikipedia.org/wiki/Sonny_Bono_Copyright_Term_Extension_Act
After the 1976 copyright extension, the U.S. put people like Ronald Reagan (actor) as president and congress people like Sonny Bono (musician) [replaced by his wife, Mary, who ''authored'' the copyright reform and was not well versed in the matter] The phun quote being:
Actually, Sonny wanted the term of copyright protection to last forever. I am informed by staff that such a change would violate the Constitution. ... As you know, there is also [then-MPAA president] Jack Valenti's proposal for term to last forever less one day. Perhaps the Committee may look at that next Congress.
Effectively putting people affiliated/friendly with the Content Control Industries in control of the law making process. Making internal lobbying that much easier. They've effectively pushed for longer terms, by swaying Senators like Orrin Hatch who so despirately wants to be part of that scene. (Orrin Hatch is the senator who after learning about napster, said it was ok for companies to *nuke* computers found using the application. Orrin Hatch makes ""music"" and at one point had free samples on his website, loaded with DRM so that you had to own the CD to play the free sample. Genius.) In 1998 if copyright wasn't extended, Mickey Mouse would have gone Public Domain in 2003/4. They pushed things back and now it's 2023 or 2036. (that work for hire argument)