Crossing the Canadian Border with a DUI?

DUI, which is called "Impaired Driving" here is considered a criminal offence; you are absolutely correct about that. One can be considered "deemed rehabilitated" sometime after the offence, if they never get charged again. There is no set time for this, but 10 years would be close; almost certainly not after 1 year. They can check, but, my guess is that they would be denied.