Viacom's $1 billion lawsuit against YouTube for copyright infringement suffered a potentially fatal blow.

In a decision issued Wednesday, United States District Court Judge Louis L. Stanton granted YouTube owner Google's motion for summary judgment that it qualifies for "safe harbor" protection under the law. The provision of the Digital Millennium Copyright Act says that Internet companies are not liable for copyright infringement if they take certain preventive measures and promptly take down copyrighted materials when notified by their owners.

A Viacom spokesman called the decision "fundamentally flawed" in a statement and said the media conglomerate, which owns MTV Networks and Paramount Pictures, will appeal.

The surprise dismissal is a major blow to Viacom, which sued Google in 2007 and alleged that YouTube became the dominant company in online video by knowingly allowing copyrighted episodes of programs such as "The Daily Show" and "South Park."

Update, 5:25 p.m.: For much more, see the story in tomorrow's Times.

Updated, June 24: An earlier version of this post incorrectly said the lawsuit was dismissed. It has not. Instead, the federal judge granted Google's motion for summary judgment, which he did, ruling in favor of Google. Viacom can still appeal the case to the circuit court.

-- Ben Fritz