GILC Actions 



 Free Speech 





 GILC Alert 

 Mailing List
 GILC Events 




 Mail GILC 

Home Page

US Site
European Mirror


Coalition statement against "stealth blocking"

May 17, 2001

The undersigned members of the Global Internet Liberty Campaign (GILC) and the Internet Free Expression Alliance (IFEA), in keeping with the principle that end users should decide what to view and with whom to communicate, object to the practice of Internet Service Provider "stealth blocking." This concerns ISPs that do not bill themselves as filtered service providers but intentionally block their customers from accessing certain Web sites or sending mail to users at certain other ISPs. "Stealth" blocking is done undetectably, so users only see a browser error saying that a Web site is down or an email error saying that the destination mail server could not be reached. Over 99% of end users never discover that any intentional blocking is being done. and have both fallen victim to "stealth blocking" by their upstream provider, AboveNet, which blocked IFEA and GILC from sending mail to one of their member organizations between August and December 2000. During that period, AboveNet's downstream users were also blocked from viewing that member organization's Web site. The member group's hosting provider was blocked after becoming the target of a boycott by AboveNet and several other providers, due to the content and ownership of other, unrelated sites hosted by the same provider. After this practice was discovered and publicized in December, and users confirmed it was not a hoax, AboveNet abruptly halted almost all "stealth blocking" being done on its systems but did not issue any statement on the issue or say whether the practice would be reinstated.

The undersigned IFEA and GILC members are requesting a written clarification from AboveNet as to their policy of blocking customers from accessing Web sites based on their content. The members urge AboveNet to commit to not reinstate their "stealth blocking" policy in the future.

"Stealth blocking" is defined by several characteristics:

  • The vast majority of the ISP's end users are not aware of any blocking being done.
  • Even the ISP's own sales and technical support staff are usually not aware of the blocking practices, and, as the main point of contact for users, tell them that no blocking is taking place.
  • The blocking is done undetectably, creating the impression that the target Web site or the destination mail server is simply not up and running.

This would not include, for example, ISPs that cater to conservative families by advertising a filtered service, or any type of opt-in filtering system that is selected or installed by the end user. An ISP blocking an incoming flood of actual spam or any other type of denial-of-service attack as necessary to protect its network would also, of course, not be included under "stealth blocking."

The most common reason for true stealth blocking is to boycott certain hosting providers that host content that the boycott organizers believe is contributing to the problem of unsolicited bulk email (UBE), or "spam." This can even include hosting providers that refuse to host "spammers" if the provider provides hosting to companies that offer software or consulting services that are legal but can be used by "spammers." An ISP can use stealth blocking to strengthen the boycott against one of these providers, by blocking its own users from viewing all sites hosted by that provider while avoiding outrage from its own users by hiding the fact that any blocking is taking place.

The situation provides a valuable test of principle, since many GILC and IFEA members and other groups are committed to the cause of fighting unsolicited commercial email. However, we defend the right of end users to decide what content to view, whether the content is offensive to others, whether the content is published by companies that have sold products to third-party unethical marketers (spammers), or whether that content is controversial for any other reason. It is not the function of ISPs to act in loco parentis for users. Boycotts by individual, informed consumers are an admirable means of achieving a goal, but "stealth blocking" by ISPs is never justified, regardless of any noble purpose, since by its "stealth" nature it violates the principle of end user informed choice.

Constitutional guarantees of free speech in various countries are not the only safeguards against involuntary censorship. Truth-in-advertising also serves to protect users, and individuals who do not sign up for "filtered Internet service" expect that their ISP will not block their Web access or outgoing mail. If the ISP has not ensured that end users are aware of any blocking that is taking place, then the users' participation in the blocking cannot be called "voluntary."

We believe that ISPs that practice "stealth blocking" are violating consumer protection principles and restricting user choice and freedom in cyberspace.



American Civil Liberties Union

Boston Coalition for Freedom of Expression

The Censorware Project

Computer Professionals for Social Responsibility

Digital Freedom Network

Digital Rights

Electronic Frontier Foundation

Electronic Frontiers Australia

Electronic Privacy Information Center

The Ethical Spectacle


Human Rights Network

Internet Freedom


Journalism Education Association


National Coalition Against Censorship
[The positions advocated by NCAC do not
necessarily reflect the positions of each
of its participating organizations.]


Online Policy Group



Privacy Ukraine