We're Watching... Your Phone

The New York Times reports:

Most Americans carry cellphones, but many may not know that government agencies can track their movements through the signals emanating from the handset.

In recent years, law enforcement officials have turned to cellular technology as a tool for easily and secretly monitoring the movements of suspects as they occur. But this kind of surveillance - which investigators have been able to conduct with easily obtained court orders - has now come under tougher legal scrutiny.

In the last four months, three federal judges have denied prosecutors the right to get cellphone tracking information from wireless companies without first showing "probable cause" to believe that a crime has been or is being committed. That is the same standard applied to requests for search warrants.

...

Cellular operators like Verizon Wireless and Cingular Wireless know, within about 300 yards, the location of their subscribers whenever a phone is turned on. Even if the phone is not in use it is communicating with cellphone tower sites, and the wireless provider keeps track of the phone's position as it travels. The operators have said that they turn over location information when presented with a court order to do so.

Prosecutors, while acknowledging that they have to get a court order before obtaining real-time cell-site data, argue that the relevant standard is found in a 1994 amendment to the 1986 Stored Communications Act, a law that governs some aspects of cellphone surveillance.

The standard calls for the government to show "specific and articulable facts" that demonstrate that the records sought are "relevant and material to an ongoing investigation" - a standard lower than the probable-cause hurdle.

I'm not sure that cell phone tracking is as big of a problem as "privacy advocates" will claim. It reveals the approximate location of a phone (not necessarily the owner), but not the anything that a search warrant would normally be required for. It's not giving the contents of calls or the contents of homes. The information is essentially the same as (and possibly less accurate than) what could be obtained by following a suspect's public movements.

The magistrate judges, however, ruled that surveillance by cellphone - because it acts like an electronic tracking device that can follow people into homes and other personal spaces - must meet the same high legal standard required to obtain a search warrant to enter private places.

"Permitting surreptitious conversion of a cellphone into a tracking device without probable cause raises serious Fourth Amendment concerns, especially when the phone is monitored in the home or other places where privacy is reasonably expected," wrote Stephen W. Smith, a magistrate in Federal District Court in the Southern District of Texas, in his ruling.

This might make sense if the information revealed more than mere (possible) presence at a location. However, as far as I can tell the information says "suspect may be home" rather than "suspect is in his basement harvesting his marijuana plants."

For the record, the Fourth Amendment (which I do not believe applies here, for lack of search or seizure) states:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause...

Congress may need to address the issue more directly, but the 1994 standard sounds most appropriate.