Meanwhile, the U.S. Supreme Court might still decide that a dog sniffing for marijuana is NOT a search. I guess ten years from now when dogs are trained to check for diseases, it won't be a search for a dog to gather my personal medical information, either?
CrimLaw has a useful three part series on canine searches, "Canine sniffs: The search that isn't," among its notable posts, here, here, and here. Ken Lammers says that (somewhat surprisingly to me, I'll say, since not everything I've said about them has been wholly complementary) the Fifth Circuit Court of Appeals, whose jurisdiction covers Texas, Louisiana and Mississippi, in 1982 issued the ruling that sets the Fourth Amendment gold standard on the subject. Presently, though, it is in high jeopardy. In the second installment he writes:
The 5th Circuit in particular has long standing, well reasoned precedents holding that the Fourth Amendment applies with its fullest vigor against any intrusion on the human body and a dog sniff is unconstitutional "when there is no individualized suspicion." Horton v. Gross Creek Independent School District, 690 F.2d 470 (5th Cir 1982).God help us if they get it wrong; the case was argued in November (pdf), but no decision has been issued yet. For more on where this slippery slope might lead us see this Grits post.
Horton's reasoning foreshadowed the Supreme Court's finding in Kyllo v. United States. In Kyllo the Supreme court holds that there is an added expectation of privacy in a person's house and that "obtaining by sense-enhancing technology any information regarding the interior of the home that could not otherwise have been obtained without physical intrusion into a constitutionally protected area constitutes a search–at least where (as here) the technology in question is not in general public use." The dissent points out that this "would . . . embrace potential mechanical substitutes for dogs trained to react when they sniff narcotics. But . . . a dog sniff discloses only the presence or absence of narcotics does not constitute a search within the meaning of the Fourth Amendment, and it must follow that sense-enhancing equipment that identifies nothing but illegal activity is not a search either. Nevertheless, the use of such a device would be unconstitutional under the Court’s rule." The unstated inference is that Kyllo puts all the case law which has developed from the Place dicta in danger - at least when there is a heightened expectation of privacy. Personally, I am of the opinion that a technological tool and a biological tool are indistinguishable, except perhaps on an emotional level.
The Federal Supreme Court has finally accepted a case which directly addresses the question of canine sniffs in Illinois v. Caballes.
UPDATE: Talk Left has more on sniffs and searches at traffic stops, pointing to this article from the Longview (TX) News Journal.