Google’s court filing gives few new details of its legal thinking, which relies heavily on the so-called “safe harbor” provisions of the Digital Millennium Copyright Act, enacted in 1998. Those provisions generally hold that Web sites’ owners are not liable for copyright material uploaded by others to their site as long as they promptly remove the material when asked to do so by the copyright owner.

The 1998 law “balances the rights of copyright holders and the need to protect the Internet as an important new form of communication,” Google said in its filing. “By seeking to make carriers and hosting providers liable for Internet communications, Viacom’s complaint threatens the way hundreds of millions of people legitimately exchange information, news, entertainment, and political and artistic expression.”

Viacom said Google’s response misses the mark. “This response ignores the most important fact of the suit, which is that YouTube does not qualify for safe harbor protection under the D.M.C.A.,” Viacom said. “It is obvious that YouTube has knowledge of infringing material on their site, and they are profiting from it.”

Mr. Kwun, the Google lawyer, said there had been no talks between Google and Viacom to discuss a settlement. “We feel pretty confident about the case and are ready to take it to court,” he added.

In the suit, Viacom had complained that it was unfairly forced to devote significant resources to police YouTube. “Every day we have to scour the entirety of what is available on YouTube, so we have to look for our stuff,” Philippe P. Dauman, Viacom’s chief executive, said in an interview earlier this year.