Prior to the development of trade and commerce, movable property was “not esteemed of so high a nature, nor paid so much regard to by the law,” Blackstone tells us in his commentaries on the laws of England. Such property in transit was routinely confiscated by authorities or tariffed at exorbitant rates.

When commercial relations expanded, the quantity and value of personal property increased, and the law “learned to conceive different ideas of it.” Legal protection for movable property increased.

In parallel to the growth of commerce in movables centuries ago, commerce in information is on the rise today. It may be time to “conceive different ideas of it” as well—different ideas that accord information similar protection. This is what a group of amici have encouraged the Supreme Court to do in a brief on an important privacy case being argued this week.

In Clapper v. Amnesty International, the Gun Owners Foundation, Gun Owners of America, Inc., the U.S. Justice Foundation, the Downsize D.C. Foundation, DownsizeDC.org, and the Conservative Legal Defense and Education Fund have argued that the Court should recognize a property interest in confidential communications. Doing so would more clearly establish the standing of the respondents in this case to challenge the global wiretapping program Congress established in the FISA Amendments Act of 2008.

William J. Olson, lead counsel on the brief, articulated the issues well in an email distributing it:

Our amicus brief in the Clapper case extrapolates from the court’s holding in Jones and identifies the property interests at stake in this case as confidential communications that are critical to the practice of law and of the enterprise of journalism. Using a property analysis, the citizens in Clapper have a protectable property interest in their electronic communications as they do in their written communications. Thus, even though plaintiffs are not “targeted” by the Government, the Government’s contention that their search and seizure of plaintiffs’ communications is only “incidental” is unavailing.

Jones v. United States, of course, is the case decided in January, in which government agents tracked a suspect’s car for four weeks using a GPS device without a valid warrant. The Supreme Court found unanimously that this violated the Fourth Amendment. My article in the most recent Cato Supreme Court Review (2011-12) analyzes the case, and you can get a taste of that analysis in the most recent Cato Policy Report (September/October 2012).

I also discussed the Fourth Amendment status of communications in the Cato Institute’s brief in Florida v. Jardines, which is also being argued in the Supreme Court this week. The Court found Fourth Amendment protection for postal mail in an 1877 case, but stumbled when faced with the next iteration of communications technology.

In the year this Court decided Ex Parte Jackson, both Western Union and the Bell Company began establishing voice telephone services. Gerald W. Brock, The Second Information Revolution 28 (Harvard University Press, 2003). Now, instead of written messages in the post, representations of the human voice itself began moving across distance, at light speed, in a way few people understood. This is the technology this Court confronted in Olmstead v. United States, 277 U.S. 438 (1928).

The Court handled this technological development poorly. Chief Justice William Taft fixed woodenly on the material things listed in the Fourth Amendment’s search and seizure clause. Wiretapping had not affected any of the defendants’ tangible possessions, he found, so it had not affected their Fourth Amendment rights. Olmstead, 277 U.S. at 464. In dissent Justice Butler noted how “contracts between telephone companies and users contemplate the private use” of telephone facilities. “The communications belong to the parties between whom they pass,” he said. Olmstead, 277 U.S. at 487 (Butler, J., dissenting). Cf. Ex Parte Jackson, 96 U.S. 727 (1877) (“Letters and sealed packages … are as fully guarded from examination and inspection … as if they were retained by the parties forwarding them in their own domiciles.”).

Florida v. Jardines is not a communications case. The issue is whether the sniff of a trained narcotics-detection dog at the front door of a house is a Fourth Amendment search requiring probable cause. Cato’s brief invites the Court to dispense with the unworkable “reasonable expectation of privacy” test, using the plain meaning of “search” instead.

Black’s law dictionary defines “search” as “looking for or seeking out that which is otherwise concealed from view.” Smells that only trained dogs can detect are indeed otherwise concealed from humans.

Familiar though ordinary pet dogs are, a trained dog is a chromatograph. The Court should follow the Fourth Amendment’s language and precedents like Kyllo v. United States to find that a drug-dog’s sniff is a search.

A companion to Jardines, Florida v. Harris, is being argued the same day. That case will examine the sufficiency of drug-dogs as evidence of wrongdoing, an issue that has not received careful examination in the past.

So it’s a big week for the Fourth Amendment in the Supreme Court. Stay tuned for developments.