According to Local Laws and Corporate Policies: Internet Filtering on Google.cn 2008
From 2006 to 2010 Google Inc. operated Google.cn, a regional search engine specific to China, which was filtered in accordance with the People’s Republic of China’s laws on sensitive information. The objective of this research was to gain a better understanding of the pervasiveness and consistency of the Internet filtering practices that Google employed in Google.cn. This study a) tracked the presence or absence of Google’s filtering statement within Google.cn search results, and b) compared the top ten results returned from Google.ca with those of Google.cn to determine whether absent URLs were available in the Google.cn database or were filtered. All keywords were related to the topics of Falun Gong and Tibet. Data was collected in May 2008. This study found 81% of keyword searches were subject to filtering and 38% of URLs were subject to filtering; 6% of the 38% were the results of overblocking.