Disney is widely regarded as the driving force behind the most recent extensions to US copyright law. The company gets the blame for both the 1976 Copyright Act as well as the late 1990's copyright extension act, and the following video from Business Insider explains why.
With the Mickey mouse copyrights about to expire in the next few years, many expect that Disney will push for yet another extension to US copyright law (unless they're using the TPP for the same purpose).
Of course, the real kicker here is that it is doubtful that Disney actually needs a copyright to protect their properties; trademark law should be enough for that.
If Disney lets the copyrights lapse, they won't be able to protect the earliest works but they will still be able to protect the characters in those works. Disney has trademarks on virtually everything they've produced, and so long as they defend the trademarks (and keep them from being genericized) the trademarks will remain in effect.
The trademark issue is particularly important when it comes to merchandizing, which is sometimes worth more than the original work.
On the other hand, Disney wants to continue to _sell_ those older works, which means they still have a financial incentive to buy another extension to US copyright law.
found via The Passive Voice
image by Ikayama