I think it's a good idea. Whether a good idea can be translated into enforceable and legal rules is a different matter. There's a big gap between them.
In my view, I think it will be very difficult to define which country is an offshore tax haven. Many high-income countries, such as Luxembourg and the Netherlands, qualify as offshore tax havens for certain purposes. There's Bermuda and the Cayman Islands, of course. Barbados is in a different category. It is really hard for me to draft a definition that has legal effect and can be enforced within Canadian boundaries but also under public international law.
Canada is not alone. Other countries may counteract. International tax problems are complicated, because they're reflecting not only economic interest, fiscal interest and a sense of fairness among Canadians but also international relations. After all, tax law is an instrument. The Canadian government needs to do the delicate balancing that Jonathan referred to. It's a delicate dancing act. Canada needs to consider the multidimensions of the problem.