Some airports have begun using backscatter x-ray and millimeter-wave technology scanners to look for weapons and explosive devices on passengers to stop terrorist attacks. The new devices have raised privacy concerns, fueled in no small part by this YouTube video and by the prominence given to the issue at the Drudge Report. Some readers have e-mailed me wondering whether using the new technologies violates the Fourth Amendment.
I don’t have a ton of time to blog on this because I have a few major deadlines looming, unfortunately, but the short answer is that use of the new technologies is very probably lawful. The Supreme Court hasn’t weighed in on the Fourth Amendment standards for security screening at airports, but the circuit courts are basically in accord (in result, with minor variations in rationale). On one hand, the lower courts have recognized that using technology to screen for weapons or explosive devices is a Fourth Amendment “search.” On the other hand, the courts have traditionally permitted the use of such screens for airport security as reasonable (and therefore constitutional) searches in ways that give a lot of deference to the national security interest in avoiding airplane hijackings and terrorist attacks. See, e.g., United States v. Hartwell ,436 F.3d 174 (3d Cir. 2006) (Alito, J.). The basic idea is that screening to stop a terrorist attack is an “administrative search” that is constitutional so long as it is reasonable — and that it is reasonable so long as it it is not overly invasive given the threat that it is designed to deter and stop.
The question then becomes if the new technologies are distinguishable. The argument would have to be that the new technologies are more intrusive than they need to be, and that they are therefore not constitutionally “reasonable” unlike other screening technologies. See Hartwell n.10 and surrounding text. But based on cases like Hartwell, and the fact that Al Qaeda has recently tried to used PETN on a passenger to try to blow up a passenger plane, which I believe traditional screening devices can’t detect, that strikes me as an uphill battle.
Anyway, sorry I can’t give a more detailed analysis, but that’s the basic state of the caselaw.