Once he is in Canadian protected waters, he is in Canada. Hence if he is allowed on the trip, he might have a problem if Canadian authorities board the ship. Why not ask the cruise line if they will allow him to board (this must come up a lot) and if they will why not give a call to a Canadian Immigration attorney and ask what they think may happen.
I hope you all get to go.
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Whle Illinois does not consider supervision to be a conviction Canada does not recognize such a distinction. You should clear this up bc many people have been detained or turned away in Canada due to DUI. I know that after 10 years getting it absolved is much easier. I would suggest contacting a Seattle or nothern MI DUI lawyer who may have dealt with it in the past. It comes up a lot.
I know enough law in this area to be dangerous, which means I only want to add another dimension for you to think about and get specialized help with. Cruise ships that travel in international waters are an extension of the government that provides them their "flag". I'm sure you've heard of ships being "registered" in Panama, Liberia or other countries. So there is another dimension to this situation: once you board a ship that is NOT registered under US laws, you are effectively entering a foreign country. So I would check with the cruise line as to where the ship you would like to travel on is registered, and consider contacting an attorney who knows maritime law as well. While most foreign countries, both ship and foreign port of call in your case, tend to abide by American court rulings for the most part under the international law rules of "comity" and MAY consider your husband's conviction is "behind him", still if that country's laws are so strong that it would be against its public policy to recognize the supervision, then there could be an issue. Maritime law and "cruise law", sometimes known as "Admiralty" is a recognized legal specialty and you should be able to find attorneys who hold themselves out with that special knowledge.
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