A US appeals court just ruled that the US government needs a warrant to obtain mobile phone location records from your service provider. It's the third ruling at this level on the matter, and the first that says a warrant is indeed necessary. Warrantless tracking of this kind is now more likely to be heard by the Supreme Court.
Today's ruling concerns the cases of Aaron Graham and Eric Jordan, two men who were convicted for a number of armed robberies that occurred in the Baltimore area back in 2011. They were ultimately convicted as a result of cell site location information (CSLI) obtained from their carriers by court orders -- with no warrant. One order was for 14 days of records, the other was for a whopping 221 days. They appealed the convictions on the grounds that the warrantless intrusion amounted to a violation of their Fourth Amendment protections against unreasonable search and seizure.
In the two previous cases to reach the federal appeals court level, both the 5th Circuit and 11th Circuit ruled that CSLI could be obtained without a warrant because it constituted a business record kept by a third party, namely, the cell service provider. That's a dangerous precedent.
The 4th US Circuit Court of Appeals went an entirely different way in today's ruling, saying that obtaining historical CSLI for an extended period without a warrant violates people's reasonable expectation of privacy in places like their homes:
We hold that the government conducts a search under the Fourth Amendment when it obtains and inspects a cell phone user's historical CSLI for an extended period of time. Examination of a person's historical CSLI can enable the government to trace the movements of the cell phone and its user across public and private spaces and thereby discover the private activities and personal habits of the user. Cell phone users have an objectively reasonable expectation of privacy in this information. Its inspection by the government, therefore, requires a warrant, unless an established exception to the warrant requirement applies.
The decision draws on the recent Supreme Court Ruling concerning warrantless GPS tracking. In that case, the court ruled that a huge amount of GPS information created an intimate portrait of a person -- more than a person could reasonably expect to be kept private from the government's prying eyes.
The 4th Circuit builds on the GPS decision, noting that CSLI reveals a stunning amount of information, much of which should be private. You've got your phone on you at all times! In this case, the sheer magnitude of data that investigators thought they could seize under probable cause is stunning:
As it turns out, the CSLI records did reveal an impressive 29,659 location data points for Graham and 28,410 for Jordan, amounting to well over 100 data points for each Appellant per day on average. This quantum of data is substantial enough to provide a reasonably detailed account of Appellants' movements during the 221-day time period, including movements to and from the cell-site sectors in which their homes were located.
Obviously, this is a particularly egregious violation that lends itself well to consideration at a higher level in the courts. (The ACLU has a nice overview of the Graham case from a few years ago, in case you don't want to plow through the whole decision.)
But the fact that several different courts have different opinions on the matter of CSLI means it's increasingly likely the Supreme Court might consider the question sometime soon. The most recent decision is a heartening one for privacy advocates. It seems the courts are starting to acknowledge that just because you create data doesn't mean the government has an inherent right to see it.
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