Canada has three procedures for people convicted of DUI -- deemed rehabilitation, early rehabilitation, and temporary residence permits. You can get deemed rehabilitation once 10 years have passed from the time you completed all your DUI sentence obligations -- this includes your day in jail, your fine, your license reinstatement, any ignition interlock, and anything else you had to do. The 10 years doesn't begin to run until you have completed all your sentence obligations. If less than 10 years but more than 5 years has passed from completion of your affirmative sentence obligations, you can seek to get deemed rehabilitation, but this requires you complete the deemed rehabilitation form, pay the processing fee, and have it approved. This typically takes a long time. Finally, you can seek a temporary residence permit to go to Canada on a one time basis, but these TPRs depend on you persuading the Canadian border agency to let you in, which is something the border agents have a lot of discretion when they make their decision. If less than 10 years have passed since everything was done, you should not plan on going to the border without a problem.
Consult with an immigration attorney, call the state department or the embassy or visit the website.
I am a criminal defense attorney practicing in Nassau, Suffolk and New York City. The above information is not a substitution for a meeting whereas all potential legal issues can be discussed.
Sign up to receive a 3-part series of useful information and legal advice about DUIs.