Update, 4/16/13: Consumers Union, the policy arm of Consumer Reports, added its support to the call to restore the legal protection that had permitted consumers to unlock their mobile devices for use on other wireless communications networks. In letters to the FCC and leaders of the House and Senate Commerce and Judiciary Committees, the consumer group urged regulators and lawmakers to take action, whether through legislation or through Commission rulemaking. Read more at ConsumersUnion.org.

A January change to the Digital Millennium Copyright Act (DMCA) makes it illegal for you to unlock your smart phone without your carrier's permission. That is, if your phone is tethered to Carrier A, you can't "unlock" it on your own so that you can use it with Carrier B.

But this law is being questioned by consumer groups, the Federal Communications Commission, the White House, and others.

Previously, the DMCA let you unlock your smart phone or tablet. That meant that when your contract expired, you could switch carriers, say to take advantage of better service or lower rates.

(Unlocking differs from jailbreaking, which lets you load the device with the latest OS or delete unwanted bloatware. Jailbreaking an under-contract phone or tablet usually voids the manufacturer's warranty and the carrier's service agreement.)

More than 114,000 people opposed to the DMCA change have petitioned the federal government. The White House has agreed to review the matter, saying in part, "Neither criminal law nor technological locks should prevent consumers from switching carriers when they are no longer bound by a service agreement or other obligation." The FCC is also taking a closer look at the issue.

"Consumers should have control over the phones they've paid for," says Ellen Bloom, director of federal policy for Consumers Union, the policy and advocacy arm of Consumer Reports. "We are pleased that the White House and the FCC are stepping up to address this issue."