Resumen
MGM is among the entertainment industry firms that sued Grokster, Streamcast, and Sharman Networks for knowingly contributing to copyright infringement by end users of their peer-to-peer file-sharing software. In April 2003, Grokster and Streamcast persuaded a trial judge that the current versions of their programs are exempt from copyright control under the U.S. Supreme Court's decision in Sony Corp. of America v. Universal City Studios, Inc., 464 U.S. 417 (1984), which held that copyright owners have no legal right to control technologies that have or are capable of substantial non-infringing uses. MGM proposes that technologies be deemed illegal if their "primary use" is for infringing copyrights. Digital audio tape (DAT) recorders were also perceived as threatening to copyright owners. Given the tens of millions of file-sharing people, the economic efficiencies of peer-to-peer distribution and imperfections in the market for digital music, some commentators have proposed compulsory licensing regimes to enable peer-to-peer file sharing to continue while compensating copyright owners.