The Volokh Conspiracy
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The Fourth Amendment and the "Instinctive" Drug Detection Dog
This one is a search.
Lower courts are divided on the Fourth Amendment implications of a drug detection dog that jumps into a car on its own and then alerts to illegal drugs. I thought I would offer some thoughts on the problem. In my view, unprompted entry should be deemed a Fourth Amendment search. This post explains why.
First, some context. It's settled law that use of the drug sniffing dog to sniff in the area outside a car is not a search. See Illinois v. Caballes, 543 U.S. 405 (2005). It's equally clear that a search of a car occurs if the officer directs a drug detection dog to physically enter the car, the dog enters, and then the dog alerts. What courts struggle with is how to treat the dog that jumps into the car unprompted. If the officer wants the dog to stay out of the car, and it's the dog's own idea to enter the car, do you say that the dog's entry is a Fourth Amendment search attributable to the government? Or is the dog sort of its own independent actor whose instinctive conduct is not attributable to the government, and therefore its subsequent alert is not a search? See, e.g., United States v. Sharp, 689 F.3d 616(6th Cir. 2012) (holding the latter).
It seems to me that this is a question that should have a straightforward answer: An unprompted and instinctive entry by the dog, followed by an alert, is a government search. The drug detection dog is a technological tool that the government trains and brings to the scene to detect narcotics. Like most tools, it is imperfect. It doesn't always go where the government wants it to go. But it makes no sense to say that the dog loses its government character or is somehow not engaged in government action when, being led around a car, it jumps into it. If the dog enters unprompted and alerts inside the car, the government certainly uses that alert for investigatory purposes just like it would if the officer had directed the dog to enter the car. Whether the officer prompted the dog to enter shouldn't matter.
The key precedent that comes to mind is United States v. Karo, 468 U.S. 705 (1984). In Karo, the government secretly put a radio beeper in a can of chemicals sold to a narcotics ring, and they watched to find out where the bad guys carried out their crime by watching where the can went using the beeper. As long as the can stayed on public roads, there was no search under a prior case, United States v. Knotts, 460 U. S. 276 (1983). But what made Karo different is that someone—presumably one of the bad guys—brought the can into a house. The beeper thus registered its location from inside the house instead of on a public road. Karo deemed that alert from inside the house a search for the simple reason that the beeper was transmitting information from inside the home.
But wait, the government protested in Karo: They weren't in control of where the beeper went. The bad guys had brought the beeper into the house, not the government, so it couldn't predict when a search would occur and a warrant would be needed; "they have no way of knowing in advance," the government noted, "whether the beeper will be transmitting its signals from inside private premises." The Supreme Court was unmoved by this argument, basically telling the government that the unpredictability of the beeper's location was its own problem to deal with: "The argument that a warrant requirement would oblige the Government to obtain warrants in a large number of cases is hardly a compelling argument against the requirement."
It seems to me that drug-sniffing dogs in these "instinctive act" cases are a lot like the radio beeper in Karo. In both situations, the government has introduced surveillance tools to obtain information not otherwise known using normal human senses. As long as the surveillance tools stay outside the protected area, their use is not a search under Caballes and Knotts. In both situations, that Fourth Amendment rule gives agents a reason to want the tools to go near places but not go inside them. But in both situations, agents don't have perfect control, and they run the risk that the devices will go in the protected areas of the homes (in Karo) or car (in the dog cases).
Under Karo, if a suspect brings the the beeper into a home, the Fourth Amendment protection changes. Because the beeper is now in the house, a search occurs. I don't know why there would be a different result using the technological tool of a dog as compared to a technological tool of a beeper, especially given that the government has so much more control over where the dog goes as compared to where the beeper went in Karo.
