An article in the New York Times discusses police use of cell phone data.  At issue is the ability of many police departments to track the movements of individual users without ever obtaining a warrant.

..The frequency and ease with which law enforcement agencies access cellphone data to track people is difficult to assess. Civil liberties groups recently obtained data from the Justice Department through a lawsuit showing that in some jurisdictions, including New Jersey and Florida, courts often allow federal prosecutors to track the location of cellphone users in real time without search warrants.

Investigators seeking warrants must provide a judge with probable cause that a crime has been committed. But investigators often obtain cell-tracking records under lower standards of judicial review — through subpoenas, which are granted routinely, or through an intermediate type of court order based on an argument that the information requested would be relevant to an investigation.

In what would be the highest-level court decision on the issue so far, a federal appeals court in Pennsylvania is expected to rule this summer on whether search warrants are required for the most basic cellphone tracking data — the electronic footprints that cellphone users leave behind in company records, often without realizing it.

…The data obtained by the civil liberties union provides a rare glimpse into crime-fighting techniques that law enforcement agencies are reluctant to talk about. Since Sept. 12, 2001, federal prosecutors in New Jersey have gained access to cellphone tracking information without warrants in 98 investigations resulting in 83 prosecutions.

As often happens, the law has not quite caught up with technology.  Legislators need to clarify the rules on whether or not the police can force phone companies to turn over these records without a warrant.  I do not believe they should be able to.

I’m am not comforted by those officials in the article who “argue that people who obey the law have nothing to fear from cellphone tracking.” I’ve seen too many stories of rogue prosecutors who, once they have a target in their sights, refuse to ever let go, regardless of any exonarating facts later discovered.  I’m also concerned about how this kind of data could be used if law enforcement is given free access to it.  For the moment they seem content to request data only for specific cases, but can we count on that always being the case? What happens when someone gets the bright idea to analyze movement patterns and how it relates to various crimes? I can easily foresee a future where simply walking past a particular location at a particular time – a street corner known for late night drug sales, for instance – makes one a suspect in the eyes of law enforcement.

So what should be done?  As I said before, legislators need to make perfectly clear the responsibility of phone companies. It may not be necessary to say that a warrant is required if they are at least willing to clarify and clearly state that phone companies are free to refuse any request that is not accompanied by a court order.  The market would then decide the level of privacy users really want.  If they value a company that promises not to turn over records without a warrant then they’ll have that choice.  Otherwise, those who believe that the innocent have nothing to fear will be free to purchase contracts with companies that are more cooperative with law enforcement.

The important thing, in either case, is to remove the cloud of confusion phone companies face when dealing with the police.  Clarifying their obligations is an important step to ensuring our continued liberty.