Duties fixed by reference to external standards such as industry practices can operate more stringently than knowledge-based duties; for example, by imputing constructive knowledge of tortious material. This grants courts a more flexible lever with which to keep intermediary liability within proportionate bounds.

Ubiquity of the internet. The internet is now ubiquitous. Its constituent systems, networks, and protocols are essential if not always apparent features in daily life. For a majority of Britons, the internet is now their first source for locating information,3 with most consulting search engines and Wikipedia at least 12 times each day.4 Over half use Facebook and other social intermediaries to communicate with friends and conduct human relationships; one-third sell goods or services using online marketplaces such as eBay.5 Public sector cuts have seen growth in the range of government services delivered online, with more than 922 million visits to the GOV.UK portal during 2015.6 Globally, productivity tools such as online banking, email, and telephony produce an average of 144.8 billion daily messages sent to 3.4 billion email addresses.7 More than 1.5 billion people share information via social networks, hosted weblogs, and media-sharing platforms.8 These services are, in short, pervasive and indispensable to our social, economic, and political lives.