Here is a recent decision from the U.S. Supreme Court. It looks like everybody makes mistakes, even drug-detection dogs.  Good news for the police, even if the dog is wrong, you can use that for probable cause.  Bad news for citizens, if the dog is wrong, they can expand the search and look for other ways to get you in trouble.

Florida v. Harris, (9-0, Opinion by Justice Kagan, on February 19, 2013)
Summary: In a unanimous decision, written by Justice Kagan, the Court reversed the judgment of the Florida Supreme Court.  The Court held that the State has met its probable cause standard if a drug-detection dog gives an alert, even if that alert is a false positive and the State produces training and testing records supporting the dog’s reliability in detecting drugs and the defendant does not contest that showing.

Thank you,
Landon J. Ascheman, Esq.
(B) 612.217.0077 (C) 651.280.9533 (F) 651.344.0700