A US Court of Appeals has resurrected Viacom's $1bn copyright infringement suit against video-sharing service YouTube.
Judge Jose Cabranes reversed an earlier decision which had protected YouTube from damage claims under the safe harbour provisions of the Digital Millennium Copyright Act (DMCA).
According to Cabranes, YouTube may have been aware of infringements prior to takedown notifications, a violation of the DMCA which would possibly nullify the protections.
"We conclude that the District Court correctly held that the safe harbour requires knowledge or awareness of specific infringing activity, but we vacate the order granting summary judgment because a reasonable jury could find that YouTube had actual knowledge or awareness of specific infringing activity on its website," Cabranes said in issuing the ruling.
"We further hold that the District Court erred by interpreting the 'right and ability to control' provision to require 'item-specific' knowledge."
The ruling opens the door to another courtroom battle between Viacom and Google.
The two firms had previously clashed over the way YouTube handled Viacom programming, including FA Premier League matches and Comedy Central network content, which had been uploaded by users without the company's permission.
The case was thought to have been settled in 2010, when courts ruled that YouTube's efforts to stop piracy were in compliance with the safe harbour provisions.
"We are pleased with the decision by the U.S. Court of Appeals," Viacom said in a statement issued after the ruling.
"The court delivered a definitive, common sense message – intentionally ignoring theft is not protected by the law."
Google had yet respond to a request for comment on the ruling.