Any search that was enabled by a dog should be considered "fruit of the poisoned tree". Between their lack of accuracy and a dog's bias towards its handler, they should not ever serve as a basis for search or arrest.

When the justification for initial stop/search comes up in court, the dog's hit is held up as incontrovertible proof that a search was justified. Courts have upheld their use many times, all the way to SCOTUS IIRC.

This approach is far to prone to misuse by law enforcement. It's bad enough they can pull you over without cause (most states have loosely defined "irregular driving" laws), they can initiate a search of your car just as baselessly.

I think this is upside down ... the police are never going to have 'incontrovertible proof' of contraband before they do a full search by definition. If they did need such 'total evidence' to search, they wouldn't need to do the search at all ... they could just make the arrest.

And a dogs hint is not presented as evidence of a crime, merely reasonable suspicion for a search, which is what we want the tool for.

The point is to provide some degree of a reasonable basis for suspicion, after which more effort is used to determine the material outcome: either you have 1Kg of coke, or an illegal gun ... or you don't.

The entire point of the tools are to use something that demarcates reasonable suspicion; dogs, and other things, are viable tools.

If you attempt to enter a country, and you are asked where you are staying but can't provide an answer, or if you do not have a return flight - these are indications of 'reasonable suspicion' of further questioning.

SCOTUS ruling notwithstanding, I don't consider a dog a reasonable basis for suspicion. They're easily manipulated - may as well just come right out and let the police search whoever they want, because that's what dogs allow.