When the Constitution was written, its authors wanted to protect the privacy of all Americans as well as the presumption that each of us is innocent until proven guilty. These were the principles behind the Fourth Amendment protection against unreasonable search and seizure by law enforcement.
Most of the time, police cannot conduct a search without first obtaining a warrant. And even if they do obtain one, it must be limited in scope (to prevent police from just searching blindingly until they find incriminating evidence). But technology has come a long way since the Constitution was written. And unfortunately, each technological advance seems to present a new opportunity to test the limits of the Fourth Amendment.
Cellphones as surveillance tools
Thanks to the ubiquity of smart phones, nearly every American carries a tracking device in their pocket. Any app that uses location data creates a log of where we go, when we go there, and how long we stay. This data is supposed to be kept private. But increasingly, law enforcement agencies are obtaining broad warrants to search location data in order to narrow a suspect pool. These are known as “reverse location” warrants or geofence warrants, and there is considerable controversy over whether they are constitutional.
Here’s how it works. Law enforcement agencies may start with a crime scene (such as a robbed bank), and then they ask a company like Google to give information on every account holder whose smart phone happened to be near the crime scene within a certain window of time that the crime occurred.
From there, authorities can narrow the suspect pool by inputting additional criteria, finally getting detailed information on a few suspects.
Privacy vs. law enforcement powers
It would be one thing to be investigating a suspect and to obtain a warrant for his location data in order to prove he was in a given place at a given time. This would likely be considered acceptable use. It is quite another to use a treasure trove of data (invading the privacy of potentially hundreds of people) in order to generate a list of suspects.
Police and prosecutors defend the practice by saying that it is an effective crime-fighting tool. But that’s not really a justification. It might also be highly effective to put security cameras in every person’s home, but we don’t allow that for obvious reasons. In a free society, there need to be constraints on law enforcement power and a protection of privacy rights.
The new frontier
Technology and Fourth Amendment protections are the new frontier in civil rights litigation, because they will continue to play a major role in the criminal justice system. If you ever find yourself accused of a crime, please ensure that you understand how police obtained their evidence and whether you can challenge it in court.