METRO-GOLDWYN-MAYER STUDIOS v. GROKSTER

The Supreme court held that one who distributes a device with the object of promoting its use to infringe copyright, as shown by clear expression or other affirmative steps taken to foster infringement, going beyond mere distribution with knowledge of third-party action, is liable for the resulting acts of infringement by third parties using the device, regardless of the device's lawful uses.
Listen to the Supreme Court's published opinion. <[MP3]>