Internet filtering is a set of techniques that censors use to try to prevent Internet users from accessing particular content or services. Network operators can filter at any point in a network, using a wide variety of technologies, with varying levels of accuracy and customizability. Typically, filtering involves using software to look at what users are attempting to do and to selectively interfere with activities that the operator considers forbidden by policy. A filter could be created and applied by a national government or by a national or local Internet access provider. Filtering can also have very real and very harsh real world consequences. If governments monitor an individual's online activity and someone can be hauled away for writing something mildly offensive online, then it's pretty hard to argue the Web is open for them regardless of the technical architecture and freedom of the software/content.
However, advocating an entirely ‘open web’ where all things are accessible (unfiltered) to all people is also a problematic position as it is not a polar equation but a rather a position on a continuum. It seems quite clear that governmental blocking of access to Open Education Resources (OER) on the web is not acceptable where as it would be hard to take issue with the individual that sets up filters on their work PC to moderate their excessive non-work web habits (such as checking Facebook at work). Along that continuum there are many grey questions—is it acceptable for parents to establish filters to block or monitor a child’s access to pornography. Should schools be able to filter social networks like Twitter?
The question of whether filtering is appropriate often comes down the motivation for filtering and who is doing the filtering. An Open Web as we see it generally advocates for as much autonomy as possible when determining what should be filtered.
In many countries, it is no secret that government censorship of the Internet exists, as documented in the book Access Denied: The Practice and Policy of Global Internet Filtering, edited by Ronald Delbert, John Palfrey, Rafal Rohozinski, and Jonathan Zittrain (http://opennet.net/accessdenied). When a popular site is widely blocked, that fact tends to become widely known within the country.
But, in general, determining whether someone is preventing you from accessing a Web site or from sending information to others can be difficult. When you try to access a blocked site, you may see a conventional error message or nothing at all… the behavior may look like the site is inaccessible for technical reasons.
Some organizations, most notably the OpenNet Initiative (http://opennet.net), are using software to test Internet access in various countries and to understand how access may be compromised by different parties. In some cases, this is a difficult or even dangerous task, depending on the authorities concerned.
In some countries, there is no doubt about government blocking of parts of the Internet. In Saudi Arabia, attempting to access pornography results in a message from the government explaining that the site is blocked, and why. In countries that block without notification, one of the commonest signs of censorship is that a large number of sites with related content are inaccessible for long periods of time, except perhaps when they take countermeasures such as moving to a new domain. Another is that search engines return useless results or nothing at all about certain topics. These may be related to pornography, gambling, drugs (including alcohol) or other illegal activities or to political or religious movements deemed dangerous (for example, neo-Nazi sites blocked in Germany).
As discussed above, filtering or blocking is also done for a variety of reasons that have little to do with politics. Parents may filter the information that reaches their children. Many organizations, from schools to commercial companies to the US military, restrict Internet access in order to prevent users from having unmonitored communications, using company time or hardware for personal reasons, infringing copyrights, or using excessive networking resources.
However the more serious consequences of filtering come when injustices occur as a result of governments filtering and monitoring an individuals access. France, for example, passed a law in 2009 intended to control and regulate internet access through compliance with copyright law. HADOPI, as the law is called, initially proposed revoking a user’s access to the internet merely upon accusation of copyright infringement. The law was ultimately scaled back to require judicial review before pulling the plug, but the practice raises huge questions about a government that undermines a fundamental right to internet access as articulated by the European Union:
“Recognising that the Internet is essential for education and for the practical exercise of freedom of expression and access to information, any restriction imposed on the exercise of these fundamental rights should be in accordance with the European Convention for the Protection of Human Rights and Fundamental Freedoms. Concerning these issues, the Commission should undertake a wide public consultation.”
Hence the battle for an Open Web here is not just one of appropriate regulation vs autonomy but also overlaps with the age old fight for civil rights.