An edict from the Library of Congress is about to make phone unlocking illegal for the first time in 6 years. The decision, issued in October, is part of a triennial process whereby the Librarian of Congress hands out exemptions from the Digital Millennium Copyright Act.

The two previous batches of regulations, issued in 2006 and 2010, respectively, granted users permission to unlock their phones in order to switch wireless carriers. But in the wake of a 2010 decision holding that software is licensed rather than sold, the Library reversed itself and declared phone unlocking illegal once again. The Librarian was also influenced by claims that there are more unlocked phones on the market than there were three years ago.

The new ruling comes with a grandfather clause. It will continue to be legal to unlock phones purchased before Saturday, January 26. But if you unlock a phone purchased after that date you could be liable under the Digital Millennium Copyright Act, which prohibits the "circumvention" of copy protection schemes.

Obviously, this isn't what Congress had in mind when it passed the DMCA as an anti-piracy measure 15 years ago. Legislators intended for the law to bolster copy-protection schemes like those on Blu-Ray discs and iTunes content. But ever since it was enacted, manufacturers have been trying to use the law to lock down other types of media and devices. The courts have rejected efforts by the manufacturers of printers and garage door openers to use the DMCA to lock down their products. But Blizzard was more successful in using the DMCA to shut down unauthorized World of Warcraft bots. As far as we know, no one has actually been sued under the DMCA for unlocking their phone, so it's not certain how the courts would rule on the question.

It's important to note that unlocking a phone in order to take it to another carrier is different from jailbreaking it in order to install software not approved by the manufacturer. Jailbreaking is legal under the new rules—but only for phones, not tablets. And no, that doesn't make sense to us either.