Google is planning to call up two big-name US TV hosts as defence witnesses in the $1 billion YouTube copyright suit filed by Viacom. Jon Stewart and Stephen Colbert from news satire The Daily Show are mentioned in defence papers filed in the New York district court. However, both work for Viacom.

It's thought that Google is planning to call the TV stars to the stand as they have been advocates of YouTube. They have appeared in some of the site's most popular videos and have used virals to promote their offline work.

Back in March, MTV-owner Viacom produced papers that accused YouTube of "massive intentional copyright infringement of [its] entertainment properties". It said YouTube was "destroying enormous value" of its content by carrying shows on YouTube.

In contrast to Google's stance, Viacom has requested both Google and YouTube's founders take the stand. However, the witness lists will be haggled over and several reports suggest the case won't come to trial until the back end of 2008.

Force Google and YouTube into line

The suit contends that "160,000 unauthorised clips of Viacom programming" are available on YouTube. The paperwork maintains these clips have been viewed more than 1.5 billion times between them.

Viacom says its intent is to force YouTube and Google to comply with copyright laws.

Google hit back after Viacom filed its papers, saying what YouTube does is within the limitations set down by the 1998 US Digital Millennium Copyright Act (DMCA). The act is seen as one of the key definers of digital copyright in US legislation.

Alexander Macgillivray, Google's counsel, told Reuters at the time: "Here there is a law which is specifically designed to give Web hosts such as us, or... bloggers or people that provide photo-album hosting online ... the 'safe harbor' we need in order to be able to do hosting online.

"We will never launch a product or acquire a company unless we are completely satisfied with its legal basis for operating."