Getting into Canada with a DUI is a crapshoot.When you get to the gate they will ask for your passport, the guard may
A- just look at it, ask a few questions, and send you on your way
B-Scan your passport, ask if you have any offenses and see if you lie to him about it, thats when they become very irritable they dont like to be lied to
C-send you to the immigration office where they will do a full background check, possibly search your car, and basically waste half your day before sending you home.
Theres a form and a 200$ fee you can pay but as was mentioned, its still up to the discretion of the guard and you may have wasted 200$ and half a day.
I have a 15 yr old drunk driving and have to pass through the border numerous times a year for work and can honestly say it may or may not come up.If it was only 3 years ago they will more then likely not let you in if it comes up.If you lie about it and it then comes up you just committed another crime and more then likely will never get into Canada.
I carry a file, complete with everything to do with my DUI, dates, times, judgements, when it paid off etc... and a complete and current criminal background check from my state with me.The time frame for being clear to come into Canada is something like 10 or 12 years.Thats not since the arrest though, thats from the last day you completed your sentence, paid off your fines whatever you were court ordered to do.Having the dates and times saves them a lot of screwing around, and they seem to appreciate it.The current background check shows you are prepared and have been a good boy since then.
Dont bother calling the consulate, theyll tell you to take your chances at the border and thats about it.Remember, a misdemeanor down here is considered a felony up there.