http://www.csmonitor.com/2004/1110/p02s01-usju.html?s=hns
"Court to decide whether canines can sniff for drugs during a traffic violation stop.
While dog sniffs are not physically invasive, they do intrude on reasonable privacy interests," says a Chicago lawyer, in his brief to the court. "Using a drug dog during an otherwise routine stop can be intimidating, accusatory, and humiliating. A decision in the case, Illinois v. Caballes, is expected by next June."