Basic Phone Logs Can Reveal Deeply Personal Information

A recent study by researchers at Stanford University, published in the Proceedings of the National Academy of Sciences, revealed that cell-phone metadata, of the kind collected in quantity in government surveillance programs, can reveal considerable personal information about the user.  The researchers conducted a study with 823 participants whose phones provided metadata; Facebook postings were also made available through an app.  Information on more than 250,000 calls and over 1.2 million texts was collected and analyzed.

From the metadata and Facebook postings, the researchers were able to ascertain 82% of the participant’s names and cities of residence in 57% of the cases.  They were able to identify a participant’s partner, as well as businesses contacted by participants, including “hospitals, pharmacies, religious groups, legal services, firearms retailers and repair firms, marijuana dispensaries, and sex establishments.” 

The NSA previously utilized data covering a five-year span and three “hops” from a target number.  One hop would be a call from the target number to a second number; a call from that second number to a third number would the second hop.  The NSA could, from a single phone number, gather information on tens of millions of people.  Recent restrictions, including limiting the search to two hops and an 18-month period, still allows NSA analyst to collect metadata on about 25,000 people based of a single phone number.

Sources:  Ian Sample, “Even basic phone logs can reveal deeply personal information, researchers find,“ theguardian.com, May 16, 2016:  https://www.the guardian.com/science/2016/may/16/even-basic-phone-logs-can-reveal-deeply-personal-information-researchers-find.  Jonathan Mayer, Patrick Mutchler, and John C. Mitchell, “Evaluating the privacy properties of telephone metadata,” pnas.org, PNAS, Vol. 113, No. 20, May 17, 2016:  http://www. pnas.org/content/113/20/5536.full

U.S. 4^th Circuit Court Of Appeals:  Police Obtaining Cellphone Data Not A Search

The U.S. 4^th Circuit Court of Appeals held, in a 12-3 decision, that it is not a search when law enforcement asks a company for cell-phone track data.  The majority in U.S. v. Aaron Graham, decided May 31, 2016 (No. 12-4659) upheld the “third-party” doctrine, which holds that when a person gives information to a third-person there is no reasonable expectation of privacy.  The majority held: “Supreme Court precedent mandates this conclusion … For the Court has long held that an individual enjoys no Fourth Amendment protection ‘in information he voluntarily turns over to [a] third part[y].’”

The Courts for the 5^th, 6^th and 11^th Circuits have reached similar results.

Sources:  Jenna McLaughlin, “Appeals Court

Delivers Devastating Blow to Cell-Phone Privacy Advocates,” theintercept.com, May 31, 2016: https://theintercept.com/2016/05/31/appeals-court-delivers-devastating-blow-to-cell-phone-privacy-advocates/.  U.S. v. Graham:  http://pdfserver.amlaw.com/nlj/GRAHAM_ca4_20160531.pdf

by Neil Leithauser
Associate Editor

Subscriber Comments

• You must be a subscriber to view comments