Our truly wonderful colleague in the ONI, Nart Villeneuve,
director of technology at the Citizen Lab at the University of Toronto
(and, truth be told, a key element of the brains behind all filtering
research), has a timely new article in First Monday on filtering. 

His abstract: “Increasingly, states are adopting practices aimed at
regulating and controlling the Internet as it passes through their
borders. Seeking to assert information sovereignty over their
cyber–territory, governments are implementing Internet content
filtering technology at the national level. The implementation of
national filtering is most often conducted in secrecy and lacks
openness, transparency, and accountability. Policy–makers are seemingly
unaware of significant unintended consequences, such as the blocking of
content that was never intended to be blocked. Once a national
filtering system is in place, governments may be tempted to use it as a
tool of political censorship or as a technological “quick fix” to
problems that stem from larger social and political issues. As
non–transparent filtering practices meld into forms of censorship the
effect on democratic practices and the open character of the Internet
are discernible. States are increasingly using Internet filtering to
control the environment of political speech in fundamental opposition
to civil liberties, freedom of speech, and free expression. The
consequences of political filtering directly impact democratic
practices and can be considered a violation of human rights.”

A relevant finding for the swirling debate over China and the role of
US corporations: “Countries such as Iran, Saudi Arabia, United Arab
Emirates (UAE), Tunisia, Yemen and Sudan all use commercial filtering
products developed by U.S. corporations.”