Elon Musk is joining a panel of experts in calling for a global ban on the development of “killer robots,” including automated weapons of all kind — from machine guns, to tanks, to drones. At first glance, this seems like common sense.

We’ve all seen the “Terminator” movies, and nobody wants violence and death raining down at the hands of soulless automata.

But this is the problem with big-government policies: They always consist of little more than wishful thinking disguised as policymaking. Sure, we can all agree that we don’t want machines to kill humans en masse, but what would be the practical effect of such a ban, and would it actually accomplish what its supporters claim?