Here’s the text from the official announcement:

“Starting next week, we will begin taking into account a new signal in our rankings: the number of valid copyright removal notices we receive for any given site. Sites with high numbers of removal notices may appear lower in our results. […]

Since we re-booted our copyright removals over two years ago, we’ve been given much more data by copyright owners about infringing content online. In fact, we’re now receiving and processing more copyright removal notices every day than we did in all of 2009—more than 4.3 million URLs in the last 30 days alone. We will now be using this data as a signal in our search rankings. […]

While this new signal will influence the ranking of some search results, we won’t be removing any pages from search results unless we receive a valid copyright removal notice from the rights owner.”

Domains with valid copyright removal notices can be found here.

Google announced that YouTube and other big websites (for example Facebook, IMDB, Tumblr and Twitter) won’t be affected by this new ranking signal.

In addition to the pure number of copyright removal notices, Google also checks other factors that influence the reputation of a site.

If you receive a copyright removal notice from Google, you should  remove the content from your website if the claim is valid. If it is a false copyright removal request, send a counter notice. Google provides a link to a counter notice in the copyright removal notices.

The new copyright signal is only one of many signals that Google uses to determine the position of a website in the search results. Google’s Amit Singhal said in the official announcement of the new ranking signal that Google “developed over 200 signals to ensure [their] search algorithms deliver the best possible results.”