Orin S. Kerr | 10.9.2025 4:17 AM

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........

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