More than 100 anti-Semitic, white supremacist and other controversial websites are currently being filtered by the French and German versions of Google, the world’s most popular search engine, according to a new Harvard Law School (HLS) report.

Released Thursday by the Berkman Center for Internet and Society at HLS by a team that earlier this fall unearthed evidence of extensive Internet censorship by the Chinese government, the report details the exclusion of content considered sensitive or illegal in France and Germany from certain foreign-language versions of Google.

One hundred thirteen websites tested from Oct. 4-21 showed google.com indexed different numbers of pages than did google.fr and google.de, the French- and German-language versions of Google—indicating that selected material has been filtered out.

Sites promoting white supremacy, Holocaust denial and anti-Semitism are among those excluded from search results. Several fundamentalist Christian and anti-abortion sites are also filtered.

First-year HLS student Benjamin F. Edelman ’02, who authored the report with Berkman Assistant Professor of Entrepreneurial Studies Jonathan L. Zittrain, said some of the filtered sites actually violate French and German post-World War II statutes against hate speech and Holocaust denial and are thus “genuinely illegal.”

But reasons for filtering other sites are not as immediately apparent.

“Most people still don’t know filtering is happening,” Edelman said.

The French and German versions of Google currently do not indicate that any filtering has been done. Users searching for excluded material receive only the message, “Your search did not match any documents.”

Search engines do not prevent direct access to websites, but limiting listings may keep users from knowing about certain sites.

Google uses geolocation systems that usually bring users in other countries directly to that country’s version of Google, though users can still access the regular English-language google.com.

The French and German filtering, which is done by Google itself, is different from third-party interception and filtering, such as the Chinese government’s restrictions on search engines.

Zittrain and Edelman said they currently do not know exactly which websites are being excluded from French and German Google and are testing restrictions through experimentation.

“When you don’t know what’s filtered, it’s basically like playing Twenty Questions,” Zittrain said.

It is also not yet clear who is asking Google to filter certain websites from its listings, he said.

“Right now, it seems it’s all being done at the level of informal requests,” probably from individuals within the countries’ respective governments, Zittrain said.