The easy rule is that you can't import anything made in a way that you couldn't legally make it here. What happens when it's technically legal, but due to local opposition you can't actually get the permit?

We saw this when California was having the blackouts (ignoring for the moment that Enron basically engineered them) and the governor said Texas should allow the California power grid to be connected to theirs. So after decades of fighting power plan construction, after decades of criticizing Texas for their pollution problems, when they come up short of power they're perfectly willing to use that smoggy power.

As far as I'm concerned, if you vote against a power plant, you should be first in line when rolling blackouts are needed. Vote against a textile mill, and you can't buy the cheap imported clothes.

Scaling this idea up to a national level isn't exactly easy, but as a guiding principal I like it better than just slapping tariffs on whatever we're trying to protect today.