Computers, Privacy & the Constitution

The Loss of Analog Anonymity

The campaign for the right to remain anonymous on the internet has been under way for some time. Proponents of digital anonymity often point to the fact that anonymity is easily achievable in the real world by pointing to pre-digital examples, such as the publication of the Federalist Papers under a pseudonym. All digital interaction leaves traces, which makes anonymity on the internet comparatively more difficult. As Daniel Solove has pointed out, "offline, people can more easily engage in anonymous transactions. I can go to a bookstore, buy a book and pay with cash, and unless people remember my face – which is unlikely – I’ll be able to buy the book with anonymity. This means that no record linking me to the book I bought is kept." However, as digital anonymity becomes more elusive, so too does real world or "analog" anonymity.

Which implies that the illustrations used by writers to make natural comparisons for people will become increasingly obsolete as the line between "digital" and "analog" worlds, which is a completely unstable and illusory boundary (unlike the boundary between zero- and non-zero-marginal cost goods) disappears.

What is RFID?

Radio frequency identification tags ("RFIDs") are an increasing threat to such analog anonymity. RFIDs are being introduced into society in numerous capacities: to replace keys, as a form of payment, to track products, for transportation and logistics, as identification both for pets and for people, and even to prevent cheating at sporting events. But what is the legal status of RFIDs? Who can scan them and when?

An RFID tag broadcasts a radio signal, which is the one fact you needed to provide that you left out. That fact is the one that makes your subsequent question probably immaterial. The tag isn't "scanned," the way a bar code is scanned: it's listened to the way a radio station or an overheard conversation is listened to. So much for Katz and all the rest of the Fourth Amendment analysis, unless you show, which you have not even undertaken to do, why—unlike WQXR-FM—there is some legal reason I can't listen to all the radios I want.

Given the Fourth Amendment's emphasis on place, the answer to this question depends upon the location of the RFID tag in question. The case Katz v. United States introduced a new test for privacy. Previously, the standard for a Fourth Amendment violation was a warrantless physical intrusion into a protected space. The Katz case held instead that warrants are required for searches in places where people have a reasonable expectation of privacy. This language contains both an objective and a subjective test for privacy: subjective, because it asks what places an individual "expects" to be private, and objective, by requiring a "reasonable" expectation. Thus, we must ask whether there is a reasonable expectation of privacy for each place in which RFIDs might be used.

No. Not without an argument you haven't made, and which it will be difficult to make.

RFIDs at Home

There is case precedent against the warrantless use of emerging technologies to search a home. Traditionally, the home is the place in which individuals have the most reasonable expectation of privacy. In the case of RFIDs, an analogy can be drawn to Kyllo v. United States, in which the court held that use of a thermal imaging device to search homes from the outside at random for indoor marijuana plants was an impermissible search. Similarly, if the police were to use RFID technology to see items inside a home, they would "almost certainly need a search warrant." The Kyllo decision states that police need a warrant to use any technology that enables them to see things which they would normally have to physically enter the house to see and that is not in general public use. Currently, RFIDs fall into this category.

However, the conclusion that scanning for RFIDs from outside a home requires a warrant is not reassuring for several reasons. The first is that this prohibition only applies to the government. Nothing would prevent a private party from scanning homes with the same technology, which is one of the reasons RFIDs have been decried as insecure. Recently, some hackers driving through the streets of San Francisco were able to scan and clone two U.S. passports that incorporated RFID technology. Additionally, warrantless searches by RFID outside the home are probably not impermissible, and even warrantless RFID searches of the home may become permissible in the future.

RFIDs at Large

A second reason to be concerned about RFIDs is that, though the police need a warrant to scan your home, they do not need one outside of that particular space. Recently, courts have ruled that there is no need for a warrant to scan a vehicle's license plate. These scanning systems do not yet use RFIDs, but as placing RFIDs into license plates becomes more popular, scanning systems that do use RFID technology will be developed. In United States v. Knotts, a police department placed a beeper inside a suspects car and used the beeper signal to track his movements. The court held that this was a not a violation of the suspects Fourth Amendment rights, stating that "visual surveillance from public places along [the] route...would have sufficed to reveal all of these facts to the police. The fact that the officers in this case relied not only on visual surveillance, but also on the use of the beeper to signal the presence of [the] automobile to the police receiver, does not alter the situation. Nothing in the Fourth Amendment prohibited the police from augmenting the sensory faculties bestowed upon them at birth with such enhancement as science and technology afforded them in this case." Thus, if the technology to track an individual by RFID is developed, there is no reason to think that police departments will not make use of that ability. Eventually, the police could track a suspect based solely upon the RFIDs that would already be on his or her person, in clothes, jewelery or even implanted under skin. And it is likely, as in United States v. Knotts , that no warrant would be required to do so.

The case is even analogically relevant only if government itself implants a tag. That's not the likely situation, right? RFID signals are just emitted radiation, like light waves that are the subject of traditional visual surveillance, or the infrared emissions picked up by night-vision goggles. Where's the issue in government looking at things that are brightly illuminated or listening to things that are noisy?

RFIDs in the Future

A final reason to be concerned about RFIDs is that as they become more common, the privacy situation may deteriorate. Both Katz and Kyllo present flexible standards. As people come to expect RFIDs to be present as they enter general public use, it may no longer be reasonable to expect not to be scanned for RFIDs, even in your home. This may not be so far-fetched: "America has seen vast increases in security measures in the wake of 9/11, which may gradually cause citizens to become "immune" to certain encroachments on their privacy." Thus, there are strong reasons to be concerned about the use of RFIDs and to begin to protect analog anonymity now.

This entire argument depends on an unestablished proposition, that the radio signal broadcast by an RFID chip is one that it somehow requires legal permission to receive. Without positive law emanating from Congress, or under an assumption of jurisdiction by FCC that might be difficult to square with existing legal rules, I think that's probably not true. There are radio broadcasts in unlicensed frequency ranges that it's not legal to listen to without permission, but they carry interpersonal voice communications that are "telephone calls" subject to constitutional protection under Title III and the illegal wiretapping statutes. RFID signals are plainly not telephone calls. So where did all the privacy come from?

This analytic error should have been found in your self-editing. In general, analytic rigor is the element on which you need to spend the most effort in revising both of these essays further.

-- StephanieTrain - 30 Apr 2010



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r4 - 17 Jan 2012 - 17:48:31 - IanSullivan
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