By 2020, Terahertz Surveillance Will Be Here, and the NYPD Will Love It

Once again, Mayor Bloomberg’s private army is in the vanguard of new surveillance technologies. The NYPD has just taken delivery of a portable machine capable of detecting the terahertz radiation emitted by every human being. It allows them to remotely detect guns or other inorganic illegal materials being concealed under people’s clothing. Suspects! We meant suspects’ clothing! We didn’t mean accidentally to suggest that the NYPD would search people just for standing around and not being guilty of anything. That would be ridiculous.

ure, it looks clunky now, but by 2020 it'll be handheld and have ten times the resolution.
Sure, it looks clunky now, but by 2020 it’ll be handheld and have ten times the resolution.

This raises some fascinating Constitutional issues, and as usual, Fourth Amendment legal superstar Orin Kerr is right on top of it:

Use of this technology raises two primary Fourth Amendment questions. First, does it constitute a search under Kyllo v. United States? More specifically, does Kyllo apply when the device is used to obtain details from inside a person’s clothes rather than inside a home? And second, if use of the device is a “search” under Kyllo, what is the standard for when such a search is reasonable? Do you match the Fourth Amendment standard for a “virtual frisk” with the existing standard for a physical frisk? Or is the virtual frisk more or less invasive than the physical frisk in a way that would require more or less cause? Interesting questions. […] A fair starting point would be to treat the virtual frisk just like they treat a physical frisk — allowing it and forbidding it in the same circumstances. Using the scanner would be a search that is reasonable only if there are specific and articulable facts to believe that the suspect is armed and dangerous. That way, the new technology does not considerably alter the preexisting balance of government power and individual rights. The government’s counterargument presumably would be that scanning to detect a gun is less invasive than actually patting someone down to find a gun: Scanning is less obtrusive because it does not involve any physical invasion or retrieval. But Kyllo suggests that this sort of more or less intrusive analysis may not apply in the case of sense-enhancing devices. And given the fact that the scanning technology itself can change over time, it’s problematic to generate a constitutional rule that may only apply to the current version of the technology — assuming that it does for that.

The problem here is that, as is the case with many digital technologies, the individual scan may be less intrusive than a hands-on frisk; but that the low cost and simplicity of digital frisking may result in mass scanning, which would pose (we think) a Fourth Amendment issue separate from and much more serious than whether a single scan was constitutional. The courts may not be ready to grapple with it, but it’s coming, so the people better be ready.

Thanks to The Volokh Conspiracy and the New York Daily News for materials used in this post.

By 2020, Cellphones Will Be Able To Track You Inside Buildings Too

Science Daily reports that one of the technological limitations on cellphones’ tracking capabilities is about to be lifted.

A research team led by Professor Dong-Soo Han of the Department of Computer Science at the Korea Advanced Institute of Science and Technology has developed a way of locating cellphones using their WiFi fingerprints to within 10 meters in indoor locations in cities.

The article is pretty gung-ho about the capabilities of this new technology, though they also report Professor Han as suggesting that “There seems to be many issues like privacy protection that has [sic] to be cleared away before commercializing this technology.”

Yes, Professor Han. That may be something of a concern.

In particular, may I ask, pretty please, that legislators considering bills to protect the privacy of cellphone users’ location data, bear in mind that this kind of indoor location detection has been shown to be possible? I give law enforcement oh, about five minutes after the commercial release of this technology before they start using it in investigations.

H/T to the ACLU for this graphic
H/T to the ACLU for this graphic

The obvious Fourth Amendment issue here is that the current rulings allowing law enforcement use of cellphone data tend to rely heavily on the fact that when you are outdoors, you are not generally held to have a reasonable expectation of privacy, and that your location is reasonably observable to members of the public. If cellphones become capable of tracking you indoors, where you do typically have a reasonable expectation of privacy, then judges will have to choose whether to weaken the Fourth Amendment further by not requiring a warrant for the seizure of cellphone data, even though it contains data that would be considered private, or to strengthen the Fourth Amendment in the light of cellphones’ increased capabilities by barring its use without a warrant. These are rough waters for any jurist, which is part of why we strongly support cellphone location privacy laws that unambiguously require law enforcement to obtain a warrant before being allowed to collect cellphone location data.

The research is reported as Hyunil Yang, Giwan Yoon, and Dongsoo Han, “Floor Accuracy Improvement of Wireless LAN based Large Scale Indoor Positioning”, IEEE MTT-S IMWS-IRFPT 2011, KAIST, Daejeon Korea, p.89-90 (2011).