Google-owned YouTube won a major victory Wednesday when a federal judge ruled the video-sharing site was protected under U.S. copyright law.

Viacom, which vowed an appeal, was seeking $1 billion in damages in a case testing the depths of copyright-infringement protection under the Digital Millennium Copyright Act of 1998.

The ruling, if it survives, is a boon for internet freedom, especially as it applies to search engines, video-hosting companies, picture-hosting services like Flickr, social-networking sites like Facebook and micro-blogging services such as Twitter. But it will make it all the more difficult for rights holders to protect their works.

In short, Wednesday’s decision says internet companies, even if they know they are hosting infringing material,  are immune from copyright liability if they promptly remove works at a rights-holder’s request — under what is known as a takedown notice.

“Today’s decision isn’t just about YouTube,” said Center for Democracy & Technology lawyer David Sohn. “Without this decision, user generated content would dry up and the internet would cease to be a participatory medium.”