I don't get it.
They don't HAVE to stop these dogs alerting to cannabis odour.
The dog isn't the one doing the actual arresting and charging FFS.
What's the problem with simply proceeding with a search based upon the dog alert, and if nothing illegal is found then the officer/s simply hands back the persons belongings and lets them continue with their day (here's your weed sir/madam, sorry for the inconvenience) .
The Constitution's fourth amendment prevents unreasonable search and seizure. The dog provides facts and circumstances that would lead a reasonable person of like training and experience to believe a crime is being committed (Aka probable cause) that makes the search or seizure reasonable.
If the dog's training alerts on something that is not illegal, then how can it provide a fact or circumstance that could change things? Dogs sometimes sit. That does not mean a person goes to jail.
What do your police CURRENTLY do in the event of a search which uncovers nothing illegal? (please don't say "plant evidence" lol)
We don't assess the reasonableness of a search on the result, but on the facts and circumstances that led to it. Lots of searches result in finding nothing.
It's not like the dog can communicate which odour it's detected, so if someone is searched and found to be in possession of something still illegal, it's not as if the 'offender' can claim it was an illegal search predicated upon the dog detecting cannabis, so the charges/conviction should be secure no?
There is no protection from illegal search and seizure if the guideline is if the government found something. The problem is in what the dog provides. It is trained to alert in the presence of illegal substances. (Some are trained for other things too, like USB's or nitrates, both legal.) If the alert no longer indicates the dog smelling illegal substances, what does the alert mean?
The dogs don't even need to be retrained.
Heck, we don't even need the dogs! If not reasonably believing a person is breaking the law is no longer important, the police can just search when they want.
Quite apart from the 'humanitarian' concerns, retiring (or God forbid, euthanising) these highly trained animals would be a huge (and unnecessary) waste of resources.
It takes years to train a good police dog and then it only has a few years of good service. Retraining will take some time and might not be worth it for all but the youngest dogs because of the service life.
Also, we have the uncertainty. The reason for the current legal framework is based on hundreds, thousands of court decisions. Court decisions where the dog alerting was based on his training in recognizing illegal substances alone. If it is now just alerting when EITHER legal or illegal things are perceived, all the factual scenarios will have to be re-litigated.