http://www.eff.org/press/archives/2010/07/26

“When one jailbreaks a smartphone in order to make the operating system on that phone interoperable with an independently created application that has not been approved by the maker of the smartphone or the maker of its operating system, the modifications that are made purely for the purpose of such interoperability are fair uses.”

“The Copyright Office recognizes that the primary purpose of the locks on cell phones is to bind customers to their existing networks, rather than to protect copyrights.”