Drug sniffing dogs and other invasions of privacy

Orin Kerr comments on one of the latest Supreme Court decisions. The Court upheld the use of drug-sniffing dogs to find illegal drugs.

One aspect of the law which strikes me as troublesome has to do with the definition of what the Fourth Amendment protects.

The mercifully short opinion for the Court by Justice Stevens relied heavily on Stevens' own 1984 opinion, United States v. Jacobsen, which had held that the police do not conduct a "search" when they perform narcotics tests because narcotics are illegal contraband; interfering with a person's drugs does not violate their Fourth Amendment rights because Fourth Amendment rights in illegal narcotics cannot be constitutionally "reasonable." While this may seem a bit odd at first, it actually has substantial roots in existing law: as I argued in a recent article, a "reasonable expectation of privacy" is not the same as the expectation of privacy of a reasonable person, but rather is a term of art keyed heavily to property law. Because a person cannot have a property right in narcotics, the thinking goes (whether rightly or wrongly), interfering with his drugs does not infringe a property right and therefore does not constitute a search.

I wonder. How far could this reasoning be extended? Could a court rule that a person doesn't have a property right in stolen property, and so a warrantless search of property for stolen property does not constitute a search? Why or why not?

I've had a bit of a debate with Eugene Volokh about one issue that appears in this decision:

One interesting aspect of today's opinion is that Justice Stevens had to distinguish the Court's 2001 thermal imaging case, Kyllo v. United States, in which Stevens had dissented. Kyllo held (more or less) that it is a search for the police to point an infrared thermal imaging device at the exterior wall of a private home. To reconcile the holding of Place with Kyllo, Stevens reasoned that the key was the nature of the information that surveillance method yielded. The thermal imaging device was used to obtain intimate details in the home, whereas the drug-sniffing dog only indicated the presence or non-presence of illegal narcotics. ... In particular, dogs can sniff narcotics from the exterior of a car because the bags holding the narcotics are not perfectly sealed; some of the drugs leak out into the open, and the dogs can smell that. In the language of Stevens' Kyllo dissent, this was "off the wall" surveillance, not "through the wall" surveillance. But Stevens had no room to make this argument after Kyllo, so he had to focus on the nature of the information obtained rather than the way the search was conducted.

In the debate, the subject was radiation monitors which might be used to find nuclear weapons hidden somewhere in a city. The question was, could you use radiation detectors to locate a cache of fissile material in someone's home?

(Eugene referred to "Geiger counters", but these, and indeed, any gas-filled detector, are not the best instruments to use to find fissile material.)

Eugene spent a great deal of energy on the issue of how a non-directional radiation detector could be used to obtain information about what's going on inside a private dwelling. In the case of a person using a radiation monitor, he could stand on the street outside an address and measure levels of ambient radiation. Such a monitor is usually not directional, though with some effort it could be made directional. (Moving it from one side of the car to the other would give you some spatial discrimination, for example.) Absent any built-in or improvised directional resolution, the investigator would have to move the instrument from place to place and observe how ambient levels changed. At best, he'd be able to show that radiation levels rose as you got closer to a particular address. With this information, you could obtain a search warrant. You are not building an image of the distribution of radiation sources inside the building. Or, if you want to build a plot of radiation levels and call that an "image", it is one with resolution that is coarser than the size of the building involved.

A thermal imaging device, on the other hand, builds an image using infrared radiation which penetrates the wall of a building. It is a device which is capable of directly recording very precise spatial information in an area that is inside the boundary of private property. The image it can be used to create has a resolution that is finer – by a good margin – than the size of the building.

Maybe that's the ticket.

As long as the smallest object you can resolve with whatever imaging/detection technology you have is larger than the boundary of the private area you are searching near, it's OK to use that particular imaging/detection technology to obtain information about what's going on inside that area.