Phone Tracking And The Law: Clear Sailing

Written by Mark Rasch
February 21st, 2013

Attorney Mark D. Rasch is the former head of the U.S. Justice Department’s computer crime unit and today serves as Director of Cybersecurity and Privacy Consulting at CSC in Virginia.

In the ongoing Nordstrom/Euclid cell phone tracking debate, it seems that Nordstrom (NYSE:JWN) failed to ask all three necessary questions when using any technology that might raise a privacy concern. These questions are, in no particular order: Is it legal? Is it profitable? And is it wise? Ask only two of these three questions, and you can be in deep trouble.

The debate surrounds the Seattle-based retailer’s use of a vendor called Euclid, which captures information from the Wi-Fi signals of both customers and passersby.

Is it legal?
There is no specific U.S. law on whether MAC addresses are “personal information” entitled to legal protection. Moreover, U.S. law regarding things like access to cell phone records and cell phone usage probably don’t apply to the Wi-Fi portion of the device. So although it may constitute an unlawful “trap and trace” or “pen register” to capture a cell phone number or IMEI of a cell phone, these laws likely don’t apply to capturing the MAC address of a Wi-Fi-enabled device. Put simply, your iPad or Wi-Fi-enabled iPod isn’t a phone, nor is the non-phone portion of your iPhone, Blackberry, Android or Windows mobile device.

So the “ping” is probably legal. Or better yet, probably not expressly prohibited under current U.S. law (lawyer tip—always equivocate. Always.).

The next question is whether a MAC address is “personal information.” Generally, a MAC address would not be considered personal information, any more than the serial number of your toaster would be personal information. It identifies a device, not a person, and it reveals no information about that device except the manufacturer and that it is a device. Big fat hairy deal, right?

But a Wi-Fi-enabled device does reveal a lot more than a toaster. And a MAC address can reveal intimate personal information, depending on how it is used and what information it is used with.

For example, Valentine’s Day was last week, and you and your girlfriend (each with a separate device) strolled into Nordstrom. The Euclid sensor picks up the unique MAC addresses and follows the two unknown devices into the store. Yours veers off to hardware (I know, Nordstrom doesn’t have hardware, but stay with me here) and hers walks to to women’s shoes. Hmm. I detect a pattern. You then meet at jewelry and stay there for about 15 minutes. You leave together. Personal information? Maybe.

A few hours later, your MAC address again pings the store. This time, it’s accompanied by an entirely different MAC address. This time, it’s your wife’s MAC address. Busted! Hard to say that the MAC address with the traffic data is not, in some way, “personal.”

Now we add the anti-theft cameras, the parking lot cameras capturing license plate information and even the registers themselves. Pretty easy to turn an anonymous MAC address into a real-life, real-time profile of a specific person. And each bit of information is perfectly legal to capture.


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