Gizmodo points to some outré technology on the Department of Homeland Security’s drawing board.

Within the next year or two, the U.S. Department of Homeland Security will instantly know everything about your body, clothes, and luggage with a new laser-based molecular scanner fired from 164 feet (50 meters) away. From traces of drugs or gun powder on your clothes to what you had for breakfast to the adrenaline level in your body—agents will be able to get any information they want without even touching you.

I don’t know about each of the technologies in this article, but the one I do know of—Raman spectroscopy—works by exciting a molecule with a laser. When the molecule returns to its normal state, it gives off a distinct photon that can be treated as a signature of the molecule. Thus, munitions and drug detection becomes “easy.”

Here’s why “easy” is in scare-quotes: At anything other than a very small distance, you have to shine a very high-intensity laser and have very sensitive detection equipment to gather the signature. The laser would fry people’s skin and burn their retinas, and the sensor would probably not work in the noisy, dusty areas where they might use these devices. There may be some new technology that defeats these challenges of physics, of course, but I hope not.

The article says there has “so far been no discussion about the personal rights and privacy issues involved.” Not true!

On page nine of Cato’s brief to the Supreme Court in Florida v. Jardines, we noted this developmental technology as an example of something that could perform quite invasive analysis without being a “search” under the Jacobsen/Caballes corollary to the “reasonable expectation of privacy” test from Katz v. United States.

The doctrine that arose from Katz was that a Fourth Amendment search occurs when one’s reasonable expectations of privacy are upended by government action. When government action only detects only illegal drugs, such as when a drug-detecting dog sniffed Caballes’s car, this is something in which a person can have no reasonable expectation of privacy, so no search has occurred. Get it?

Technologies like remote Raman spectroscopy illustrate the absurd result Katz doctrine produced in Jacobsen and Caballes. Katz and the Jacobsen/Caballes corollary are junk.

Cato’s Jardines brief points out the better way to administer the Fourth Amendment: When government agents use uncommon technology to perceive otherwise imperceptible things, that is searching. If the searching is appurtenant to our persons, houses, papers, and effects, it must be reasonable. In the vast majority of cases, that means getting a warrant.

Lasers won’t be the end of privacy if I can help it.