Viacom claims in a New York federal court appeal that YouTube allows – and even welcomes – "rampant copyright infringement."
A lower court previously concluded that Google's popular video service is protected from copyright infringement claims. On Tuesday, Viacom urged a Manhattan appeals panel to reject that ruling.
Viacom lawyer Paul Smith says YouTube gets a free ride on the backs of other's copyrights.
Google attorney Andrew Shapiro counters that YouTube follows the law.
He says that when YouTube is told of a copyright infringement, it always takes down the video.
The New York-based Viacom owns popular cable channels such as MTV, Comedy Central and Nickelodeon. Google is based in Mountain View, Calif.
It could take months for the appeals panel to rule.