For the second time in three years, a federal judge has dismissed Viacom's $1 billion copyright lawsuit against YouTube, saying the online video site doesn't have to police itself as long as it removes infringing videos when copyright owners give notice.

U.S. District Court Judge Louis Stanton in New York ruled Thursday that Viacom never proved YouTube was aware of thousands of videos Viacom said were stolen from its TV networks such as Comedy Central and BET.

Viacom Inc. said it will appeal.

"This ruling ignores the opinions of the higher courts and completely disregards the rights of creative artists," the company said in a statement.

The ruling upholds Stanton's original decision from June 2010 and leaves in place the current understanding of the Digital Millennium Copyright Act of 1998. Stanton also ruled that YouTube did not act with "willful blindness" to the issue, noting that in 2007 it removed 100,000 videos in one day after being notified by Viacom they were infringing.