In a post entitled "Carbon tariffs — the legal aspects," Paul Krugman quotes Joost Pauwelyn as saying:
In sum, if carefully calibrated along the lines suggested above, carbon equalization measures at the border, imposed on certain imports, can be modeled in compliance with WTO non-discrimination rules and/or the WTO’s environmental exception.
Krugman then says:
So the economics are right; it’s WTO-legal; and it would neutralize a major political argument against controlling greenhouse gases. Why, oh, why, would Obama say “Ni”?
I think Krugman is overstating things when he draw the conclusion "it's WTO-legal" (that is, carbon tariffs are WTO-legal) from Joost's statement. Joost was careful to say that such tariffs "can be" legal "if" designed in the right way. Whether this condition will be met is far from clear.
