Even if banning PoW were agreeable on logical grounds (ie, overcoming the arguments of the sibling comments to this one), is there any reason to believe that such a law will:

* Reduce trade * Reduce value * Reduce carbon use?

Is there a case ever where an illicit market found a price equilibrium which was lower than the licit one? And, if such a ban does cause the price go up, won't the same incentives cause continued mining competition?