My previous blog posts on drug sniffing dogs have flirted with this issue. Commenters seem most inflamed by it. Yet, it is dogma that there is no Fourth Amendment right to privacy in possessing contraband. The rationales animating the Fourth Amendment currently protect those who are ultimately found to possess contraband only as a way to shield the innocents, who do not possess contraband but may have other embarrassing items in their possession. According to the Supreme Court, we protect the guilty only to safeguard the innocent from intrusive government action.
Because the Court has held that there is no reasonable expectation of privacy in contraband, intrusions that are “binary,” or test only for the presence or absence of contraband, do not implicate Fourth Amendment rights. Thus, police officers may use drug sniffing dogs, test white powder for cocaine, or use child pornography detection software to search only for digital contraband without any suspicion justifying their actions. (This does not mean that law enforcement can use any means to do so, and Florida v. Jardines will test how intrusive binary searches can be, but I do not believe that Jardines will overturn the proposition that no suspicion is needed before using a drug sniffing dog in a less intrusive way.)
The Seventh Circuit has even extended this logic to hold that there is no reasonable expectation of privacy in illegal activity, no matter where it occurs. The Court of Appeals in United States v. Brock, 417 F.3d 692 (7th Cir. 2005), allowed a canine sniff at the door to a man’s room once his roommate consented to allow the police access to the home. This would be one way of deciding Florida v. Jardines, although I doubt the Supreme Court will go as far as the Seventh Circuit. If you’re interested in the “contraband exception” to the Fourth Amendment, check out Timothy MacDonnell, Orwellian Ramifications: The Contraband Exception to the Fourth Amendment, 41 U. MEM. L. REV. 299 (2010).