This spring, lawyers for MGM Studios argued before the U.S. Supreme Court that Grokster, the maker of a peer-to-peer Internet file-sharing system, should pay damages to copyright holders for facilitating mass piracy of their digital content.

One simple fact underlies the current debate over intellectual-property rights, the theme of this special issue of Technology Review: every time you download a music file or use some other artifact of digital culture, you are making a copy. If you don't have permission, or the use is not "fair" (that is, very limited), you may be breaking the law and infringing the rights of copyright owners. Until recently, there was little that copyright owners could do about it; but there are now effective digital rights management (DRM) technologies designed to limit copying, remixing, and redistribution. Is this increase in the potential power of copyright owners a good thing?