There isn't much need to argue. People traveling to/from international destinations can be easily searched under a number of different theories. Fly Vancouver>Vegas and you can be searched in Vegas despite having already been searched in Vancouver. Sometimes if they find something in Vancouver they will still put you on the plane as arresting you for a US crime in Vegas is much cheaper than in Vancouver (normally done for people with outstanding warrants).
It's not just cheaper they are not allowed to arrest you in Canada. They can only deny entry or detain you until the Canadian authorities make the arrest.
Actually in Vancouver, before you clear customs to get on your flight to the US, you enter a secure area where there is a sign that says welcome to the US of A, and you are in fact on US soil, just like an embassy, I'm pretty sure they could even fly you directly to a Bellingham jail and the Canadian government/RCMP couldn't do a thing about it once your cRoss that imimaginary line in the airport.
> Preclearance facilities exist because of agreements made between the U.S. federal government and the governments of the host countries. Travelers who have passed through the U.S. government checks, but whose flight or ship has not departed, remain in the legal jurisdiction of the host country.
