Issues around data capture, retention and control are gaining significant attention in many Western countries — including in the UK. In this piece originally posted on the Ethics Centre Blog, the OII’s Brent Mittelstadt considers the implications of metadata retention for privacy. He argues that when considered in relation to individuals’ privacy, metadata should not be viewed as fundamentally different to data about the content of a communication.

From 13 October onwards telecommunications providers in Australia will be required to retain metadata on communications for two years. Image by r2hox (Flickr).

Since 13 October 2015 telecommunications providers in Australia have been required to retain metadata on communications for two years. Image by h2hox (Flickr)

Australia’s new data retention law for telecommunications providers, comparable to extant UK and US legislation, came into effect 13 October 2015. Telecoms and ISPs are now required to retain metadata about communications for two years to assist law enforcement agencies in crime and terrorism investigation. Despite now being in effect, the extent and types of data to be collected remain unclear. The law has been widely criticised for violating Australians’ right to privacy by introducing overly broad surveillance of civilians. The Government has argued against this portrayal. They argue the content of communications will not be retained but rather the “data about the data” – location, time, date and duration of a call.

Metadata retention raises complex ethical issues often framed in terms of privacy which are relevant globally. A popular argument is that metadata offers a lower risk of violating privacy compared to primary data – the content of communication. The distinction between the “content” and “nature” of a communication implies that if the content of a message is protected, so is the privacy of the sender and receiver.

The assumption that metadata retention is more acceptable because of its lower privacy risks is unfortunately misguided. Sufficient volumes of metadata offer comparable opportunities to generate invasive information about civilians. Consider a hypothetical. I am given access to a mobile carrier’s dataset that specifies time, date, caller and receiver identity in addition to a continuous record of location constructed with telecommunication tower triangulation records. I see from this that when John’s wife Jane leaves the house, John often calls Jill and visits her for a short period from afterwards. From this I conclude that John may be having an affair with Jill. Now consider the alternative. Instead of metadata I have access to recordings of the calls between John and Jill with which I reach the same conclusion.

From a privacy perspective the method I used to infer something about John’s marriage is trivial. In both cases I am making an intrusive inference about John based on data that describes his behaviours. I cannot be certain but in both cases I am sufficiently confident that my inference is correct based on the data available. My inferences are actionable – I treat them as if they are reliable, accurate knowledge when interacting with John. It is this willingness to act on uncertainty (which is central to ‘Big Data’) that makes metadata ethically similar to primary data. While it is comparatively difficult to learn something from metadata, the potential is undeniable. Both types allow for invasive inferences to be made about the lives and behaviours of people.

Going further, some would argue that metadata can actually be more invasive than primary data. Variables such as location, time and duration are easier to assemble into a historical record of behaviour than content. These concerns are deepened by the difficulty of “opting out” of metadata surveillance. While a person can hypothetically forego all modern communication technologies, privacy suddenly has a much higher cost in terms of quality of life.

Technologies such as encrypted communication platforms, virtual private networks (VPN) and anonymity networks have all been advocated as ways to subvert metadata collection by hiding aspects of your communications. It is worth remembering that these techniques remain feasible only so long as they remain legal, one has the technical knowledge and (in some cases) ability to pay. These technologies raise a question of whether a right to anonymity exists. Perhaps privacy enhancing technologies are immoral? Headlines about digital piracy and the “dark web” show how quickly technologically hiding one’s identity and behaviours can take on a criminal and immoral tone. The status quo of privacy subtly shifts when techniques to hide aspects of one’s personal life are portrayed as necessarily subversive. The technologies to combat metadata retention are not criminal or immoral – they are privacy enhancing technologies.

Privacy is historically a fundamental human value. Individuals have a right to privacy. Violations must be justified by a competing interest. In discussing the ethics of metadata retention and anonymity technologies it is easy to forget this status quo. Privacy is not something that individuals have to justify or argue for – it should be assumed.


Brent Mittelstadt is a Postdoctoral Research Fellow at the Oxford Internet Institute working on the ‘Ethics of Biomedical Big Data‘ project with Prof. Luciano Floridi. His research interests include the ethics of information handled by medical ICT, theoretical developments in discourse and virtue ethics, and epistemology of information.


Note: This post was originally published on the Policy & Internet blog on . It might have been updated since then in its original location. The post gives the views of the author(s), and not necessarily the position of the Oxford Internet Institute.