What do printer cartridges, garage door openers, and universal power supply calibrations have in common? They all use copyrighted code, they all feature technological impediments to unauthorized execution of their code -- and now they've all been the focus of appellate litigation under the Digital Millennium Copyright Act (DMCA).
One of the most-litigated and most-argued provisions of the DMCA is section 1201, the "anti-circumvention" provision which forbids breaking or bypassing certain technological measures that protect copyrighted works. Broadly speaking, section 1201(a) deals with technological measures that restrict access to a copyrighted work, and 1201(b) deals with copy controls and other measures that restrict not your access to a work but what you can do with the work after accessing it. Section 1201(a) forbids both trafficking in circumvention tools and the act of circumvention itself; 1201(b) covers only trafficking. An ongoing source of controversy is whether and how closely 'access' under 1201(a) must be tied to an underlying act of copyright infringement before circumvention liability will attach. To put it another way, is what you were going to do with a work once you accessed it relevant to the question of whether you're allowed to grant yourself access? Different appellate courts have come down on opposite sides of this issue, and another circuit court just waded into the mix.