There might be a few good reasons to treat one product, or one geographical or climatic region different from another, with an effect on the state or province that's heavily into that product. In that case, a smart national government makes compensatory moves or finds some other way to spread the load. The "compelling government interest" standard down here means the government has to prove both that the interest it's pursuing is so great that it justifies abrogating rights, and that it has tailored the legislation in the narrowest possible way to meet the interest.
I miss Harper.