Certainly in terms of international tax havens, they exist because we allow them to exist. We allow them to exist in the sense that we don't require corporate entities operating in Canada to disclose where they declare profits, where they make revenue or where they employ people in this country. As a result, we can't tax them appropriately.
If you are a Canadian organization in Canada, you can't play these sorts of games, because you're required by law to declare where you employ people and where you make your revenue. You pay your corporate income taxes in the jurisdiction where those two things happen; you can't just declare all of your money in the jurisdiction where the corporate tax rate is the lowest.
Internationally, you can; therefore, we allow that. I think one of the big pieces in terms of the closing these types of tax loopholes is fundamental transparency about where companies that operate in Canada make their money and who they employ.
Certainly, their closure is a potential source of government revenue in Canada. At present it's simply being shifted overseas, and no one is paying tax on it.