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.

Google’s policies in the area of filtering requests are not yet clear, he said, noting that the “American vision of free speech” may not be the final word in Google’s foreign policies.

“Google does not yet have a clear, well-articulated public policy,” Edelman agreed.

“We carefully consider any credible complaint on a case-by-case basis and take necessary action,” Google spokesperson Nathan Tyler told the Associated Press in a statement last week.

The report on Google filtering came in the midst of an ongoing Berkman study of China’s Internet blocking practices. Sharp-eyed “netizens” first alerted Zittrain and Edelman to discrepancies in French and German Google search results, and the two ran checks on other sites known or presumed to contain controversial material.

Their report, published at http://cyber.law.harvard.edu/filtering/google, is interactive—readers can view filtered sites and check in pop-up windows whether the sites are still banned on google.fr or google.de.

A few sites that once contained controversial material remain filtered, even though their content has changed or the domain is now empty.

“Blacklisting by Google continues long after,” said Edelman, adding that it is unclear how often, if ever, Google re-examines filtered sites.

The authors are currently asking the public to alert them to additional discrepancies in search results.

“We’re trying to get a sense of how much filtering is being done, how many resources are being put into the filtering,” Zittrain said.

They also plan to study Internet use in the United Arab Emirates, Vietnam and Spain.