Online policing should abide by democratic principles

In 201l, the US Federal Bureau of Investigation identified Timothy Carpenter as the ringleader of a string of armed robberies in Michigan and Ohio.

- RAHUL MATTHAN

Instead of obtaining a search warrant to gather evidence, they chose to obtain a court order compelling his mobile carrier to hand over cell-site location data. This allowed investigators to review Carpenter's digital history—across a total of 12,898 separate location points—and map his precise movements over a four-month period. Armed with this data, the prosecution was able to place him at the scene of the robberies using his own cellphone data and secure a conviction.

The digital trails we leave behind have given law enforcement new ways to investigate crimes. In addition to location information (used in the Carpenter case), sleuths can access a range of other data sources, such as messages exchanged and digital payments made, to uncover criminal activity that would have otherwise gone undetected. While governments around the world have moved aggressively to expand their surveillance capabilities, the methods they are adopting threaten longstanding constitutional protections.