ISPs may use a wide range of technologies that allow them not only to violate the network neutrality (i.e., the principle that all Internet packets shall be treated equally) but also to restrict the freedom of expression of Internet users. These techniques allow, e.g., the ISPs to block DNS requests (as well as IP packets), to tear down TCP connections, to tamper with the original content of IP packets. In many cases, such techniques are used to comply with the requests coming either from judges or from other independent authorities (e.g., HADOPI). In other cases, instead, the network neutrality may be violated by an ISP for commercial purposes (e.g., to inject advertisements into a web page).

In general, the topic of network neutrality has been discussed by computer scientists, economists and lawyers. To complement these points of view, network neutrality studies (and especially studies concerning the blocking of content) could greatly benefit from sociological insights that also consider the role of the users, as well as the impact of such network neutrality violations on the users. In particular, it is interesting to empirically investigate the many ways in which users may be prevented from accessing content, the related impact on the user freedom to access information, and the possible countermeasures that users can implement to circumvent the censorship.