Washington ? Owners of the iPhone will be able to legally unlock their devices so they can run software applications that haven’t been approved by Apple Inc., according to new government rules announced Monday.

The decision to allow the practice commonly known as “jailbreaking” is one of a handful of new exemptions from a 1998 federal law that prohibits people from bypassing technical measures that companies put on their products to prevent unauthorized use of copyright-protected material. The Library of Congress, which oversees the Copyright Office, reviews and authorizes exemptions every three years to ensure that the law does not prevent certain non-infringing uses of copyright-protected works.

For iPhone jailbreakers, the new rules effectively legitimize a practice that has been operating in a legal gray area by exempting it from liability. Apple claims that jailbreaking is an unauthorized modification of its software.