Canada allows entry if you have a DUI conviction.
For years I have advised clients that a single DUI will bar entry into Canada for ten years and two convictions will bar you for life. Starting March 1, 2012, some of that will change. Immigration Canada has bowed to pressure for the Canadian tourist industry. Those businesses were losing millions of dollars every year because customers were being turned back at the border.
Under new policies people with one DUI that is not too recent will be permitted to enter Canada on a Temporary Resident Permit without a fee. People with more than one criminal conviction, whether they are DUI’s or other crimes, will still be barred unless they an obtain a TRP or a certificate of rehabilitation under the old rules.
You should still plan ahead. It is not clear yet how recent or how serious a DUI must be to bar you. You should contact Immigration Canada at the Point of Entry where you plan to enter Canada to determine their interpretation before you go.