I've always believed that, in terms of using dogs as drug sniffers, it's a form of a search. I realize it was challenged in the SCOTUS and then thrown out, but it always seemed like a search to me. Don't have probable cause to search someone's car? Don't worry, have this dog search the car and if it "hits" on something then we have probable cause. Dogs don't normally run about sniffing for marijuana, you have to train them to do so. In which case, how's it really different than having some electronic device that can test the air around a car to see if it has drugs in it? The dog is specifically trained to search an area the trainer tells it to, and if it gives its trained sign, then good boy and search the car. I find that drug dogs are a violation of the 4th.
The accuracy of them is rather questionable and I have to wonder (and I doubt they keep track of this) what the false-positive rate is. Once a drug dog is "alerted" then cops can proceed as if its a drug case, search, seize money, car, etc. even if drugs aren't found.
In other actions of police duty, dogs may find a more appropriate role, but as drug sniffers...all they do is generate "probable cause". There's nothing reliable about their service in this means.
