1893 - Thomas Edison received two U.S. patents. The first was for a "Cut Out for Incandescent Electric Lamps" and another for a "Stop Device" (No. 491,992-3). Also No. 492,150 for "Process of Coating Conductors for Incandescent Lamps."
... by copyright holders to be unacceptable. See Professor Edward Felten's freedom-to-tinker Web site for information and pointers.
An early example of a DRM system is ...