Viacom Inc. had alleged that YouTube, which Google Inc. bought in 2006, built itself into a successful video-sharing site by promoting the unlicensed use of video taken from Viacom cable channels such as MTV, Comedy Central and Nickelodeon.
But U.S. District Judge Louis Stanton ruled in favor of Google in a summary judgment Wednesday, saying that YouTube removed illegal video promptly as required by federal copyright law.
Viacom says it will appeal.
Viacom contended YouTube's employees realized copyright-protected video was being illegally posted on the Web site, but routinely looked the other way because they knew the professionally produced material would help attract a bigger audience and encourage return visits.
YouTube lawyers have contended there was no way to know whether copyright-protected video was coming from pirates or from movie and TV studios looking to use the Web site as a promotional tool. If a studio issued a notice of a copyright violation, YouTube says it promptly removed the specified clip as required under the 1998 Digital Millennium Copyright Act.
Although other content producers also initially complained about copyright abuse at YouTube, many media companies have since struck revenue-sharing deals with the Web site.
YouTube won over much of the professional media by developing technology that automatically detects video and audio claimed by its copyright owners.