When the U.S. Supreme Court ruled, in Illinois v. Caballes, 543 U.S. 405 (2005), that police use of a trained drug-detecting dog during a lawful traffic stop does not constitute an unreasonable search, it addressed only issues the defendant had raised under the U.S. Constitution. Although the U.S. Supreme Court is the ultimate authority on U.S. Constitutional issues, the Illinois Supreme Court is the highest legal authority on interpretation of the Illinois Constitution.
In People v. Caballes, 207 Ill. 2d 504 (2003), the Illinois Supreme Court had relied on U.S. Constitutional principles in ruling that use of a drug-sniffing dog under the facts surrounding defendant's traffic stop was not justified. So, when the U.S. Supreme Court ruled that the dog sniff did not violate the U.S. Constitution, it remanded the case to the Illinois Supreme Court to consider the issues the defendant had raised under the Illinois Constitution.
Yesterday, in People v. Caballes, No. 91547 (Ill. May 18, 2006), the Illinois Supreme Court released its decision on the issue of "whether, even though the canine sniff of defendant's car during a routine traffic stop did not implicate the fourth amendment, it nevertheless violated the guarantees of the state constitution."
The Illinois Supreme Court held, in a lengthy 4-3 decision, that use of a trained drug-detecting dog during a lawful traffic stop does not violate the search and seizure provision of article I, section 6, of the Illinois Constitution of 1970. The Court also held that a dog sniff of a vehicle does not violate the privacy clause of article I, section 6. Finally, the Court ruled that drug-sniffing dogs are generally reliable.
Photo of Illinois Supreme Court building from the Illinois Courts official site.