Jailbreaking Cell Phones Is Legal

The Librarian of Congress has posted that jailbreaking cell phones and other wireless devices is legal, so if you want to jailbreak you new cell phone, go for it.

Persons who circumvent access controls in order to engage in noninfringing uses of works in these six classes will not be subject to the statutory prohibition against circumvention.

And this is the section that relates to cell phones:

(2) Computer programs that enable wireless telephone handsets to execute software applications, where circumvention is accomplished for the sole purpose of enabling interoperability of such applications, when they have been lawfully obtained, with computer programs on the telephone handset.

(3) Computer programs, in the form of firmware or software, that enable used wireless telephone handsets to connect to a wireless telecommunications network, when circumvention is initiated by the owner of the copy of the computer program solely in order to connect to a wireless telecommunications network and access to the network is authorized by the operator of the network.

You can read more about it at The Library of Congress.