It is becoming increasingly common for copyright owners to use the Digital Millennium Copyright Act (DMCA) (17 U.S.C. �1201(a)(1)) to prevent people from circumventing a technological measure that effectively controls access to a copyrighted work.

For example, in the past the mobile phone industry has applied the DMCA to create software locks that control user access to particular firmware in a mobile phone. The main types of software locks used in mobile phones were: service provider code locks, system operator code locks, band order locks and subscriber identity module locks. Since the firmware in the mobile phone is a copyrighted work, any attempts to circumvent these software locks in a mobile phone to gain unauthorized access to the firmware could be actionable under the DMCA.