U.S. President Barack Obama has sealed his stamp on a new law that makes unlocking a cell phone legal again.

The Unlocking Consumer Choice and Wireless Competition Act, which was passed with a unanimous vote in Congress last month, repeals a widely ridiculed a 2013 decision by the Library of Congress that declares cell phone unlocking a violation of the Digital Millennium Copyright Act (DMCA).

The DMCA prevents Americans from "circumventing" technologies that prevent copyright infringement and grants the Library of Congress to grant exemptions. In 2006 and 2010, the Library of Congress declared cell phone unlocking one of the technologies exempted from the law, but refused to renew this exemption last year. With the Library's decision to classify cell phone unlocking as illegal, any cell phone owner who wishes to have his phone unlocked can be punished by no less than five years imprisonment.

Many cell phones sold by U.S. carriers have a software lock that prevents users from using another operator's SIM on the phone, even after the usual two-year contract imposed by most carriers has expired. Cell phone unlocking is particularly beneficial for customers who wish to take their cell phones with them to another carrier or frequently travel to other countries and prefer to use the services of a local network instead of paying a premium for roaming charges.

The White House lauds the new law, calling it "a rare trifecta: a win for American consumers, a win for wireless competition, and an example of democracy at its best - bipartisan congressional action in direct response to a call to action from the American people."  

The law began as a bill championed by Vermont senator Patrick Leahy following a 19-month-long period during which entrepreneur and technology activist Sina Khanifar called for the legalization of cell phone unlocking and submitted a "We the People" petition that has garnered more than 120,000 signatures. It takes at least 100,000 signatures for such a petition to warrant a response from the White House.

Khanifar, who sees the law as a significant win for grassroots activism, believes much more can be than, given that the new law actually expires in 2015, during which the Library of Congress will again decide if cell phone unlocking breaches copyright laws.

"I asked repeatedly for Congress to make the exemption permanent, and Rep. Zoe Lofgren even introduced the excellent 'Unlocking Technology Act of 2013' that would have done just that," he says. "Unfortunately, Congress wasn't ready to deal with... passing a permanent exemption to the DMCA."