My understanding is that Canada is pretty strict about allowing entry from the US if you have a past DUI conviction.
My Googling suggests that an international flight beginning in the US, connecting in Toronto and going on to a final destination to a third country will possibly require going through passport control in Toronto.
Could a past conviction cause a delay/nonentry at Toronto, even if the connection is for only a few hours to switch flights?
That would seem a bit absurd if you’re only doing a connection (and not leaving the airport).
Anyone have any ideas?