Catherine Crump: The small and surprisingly dangerous detail the police track about you


Catherine Crump is an assistant clinical professor at Berkeley Law School who focuses on the laws around data and surveillance.


Police are using military style weapons, and collecting NSA style data. Automatic license plate readers mounted on police cars or beside roads are letting local police track where people are at all times. If anyone passes a plate reader, their records are kept for years. When a citizen requested their records, they found a series of photos including one of their daughters inside his driveway. The cost of storing these photos is getting lower, so the photos tend to be kept for years.

These plate readers can be abused with highly targetted tracking attempts. New York Police have driven past mosques to track attendance, and UK police have put a sketch artist on a watchlist after he drew attendees from a number of political demonstrations.

Beyond plate readers, people are tracked by mobile phone usage. By tracking who connects to a tower or multiple towers, police can get a good idea of where you are. They can also use ‘stingray’ to track a mobile phone signal within your home.

Catherine states that this is a civil liberties threat – in the past as police gain access to new technology it gets abused for criminal purposes (blackmail or political advantage) or simple curiosity / voyeurism. She wants governments to pass laws compelling police to dispose of data about innocents while allowing them to keep those under investigation.

My Thoughts

I am glad information is getting out there about what police are capable of – it is sensible to understand how our personal information is collected and used. While informative at a high level, this talk was too short to really give details, and often seemed to have an underlying paranoia / fear to it. I’m not averse to passive use of occasional license plate trackers – and the example photos given in the talk had time stamps many months apart. What is more worrying is how it is used to draw conclusions – especially if mosques are being targeted and conclusions drawn about attendees.

This is the real concern – in most cases this data will not be useful for identifying crimes. Where I travelled today will not solve anything – we are therefore taking privacy risks (and potential misuse by officers) for no gain. There is also the issue of data being used to track people who are committing no crime but violating societal convention – if they are secretly gay or having an affair this could embarrass them (or leave them blackmailed).

Reading more into Stingray (which was briefly mentioned): it mimics the actions of a mobile phone tower to force devices to connect to it. It can then track users and intercept communications.