There must be a reciprocal agreement between the two governments about this DUI thing. I know several Americans turned away at the Canadian border because of a DUI conviction, one conviction being over 40 years ago. In that case, it was an American couple crossing the border in Washington state to go RV camping. The poor wife was shocked to learn of her husband’s DUI at the border. They had to return home to their American home some 2,000 miles away.