Yes, case by case works, as long as there's honest, accurate accounting.
The truth of it is that if we live in a world where there's pricing or stringent climate policy around the world, demand will drive us in that direction. This is where the beauty of a price system is. Rather than rather than having government having to sit in through regulation and ask how it can regulate everyone's behaviour to make them behave as if there were a price, you have the market tell the truth about environmental costs, whether it's in China, Canada, the U.S., or anywhere. At that point, private investment will move us in that direction, anyway, and we won't have to have government telling everyone to behave as if the environment had a cost.