It will soon be illegal for anyone in the U.S. to unlock his or her smartphone to use it for another provider. The U.S. Library of Congress determined back in October 2012 that it was legal for consumer to unlock their smartphones, but only until January 26th, 2013.
In October 2012, the U.S. Library of Congress opinion was that ‘jailbreaking’ a smartphone was legal but never for a tablet, as per the Digital Millennium Copyright Act (DCMA) of 1996. The DCMA was set in place to protect manufacturers from hackers of their patented electronics and any kind of ‘reverse engineering’.
After years of jailbreaking smartphones so that buyers could install apps that weren't from the Apple App Store, the Library of Congress was asked to step in and decide the legality of it. The LOC's decision was that jailbreaking a smartphone was lawful but only temporarily.
The LOC decided on a 90-day grace period in which consumers could still buy a new smartphone and unlock it. Nevertheless, the library's opinion was that it was still illegal during the grace period (and beforehand) if permission was not given by one’s wireless network and always illegal for a tablet or ‘phablet’. The 90-day measure will expire at midnight on January 26, 2013.