Law and/or Policy come from any one of the three branches of government that is smart enough, or powerful enough at any given moment, to get the law, or policy, it wants by the other two branches. And don't ignore regulations. They're really neither law, nor policy, and nobody really knows how they happen sometimes, but you had better obey them!
That's the art of politics in America
Along these lines, I've always wondered where a Pres. is able to issue 'executive orders' that seemingly have no constitutional basis yet carry the force of law.......I'll forever rememeber Paul Begala's famous line about "stroke of the pen, law of the land, kinda cool"......how ridiculous would it be to have that kind of power in the hands of Pres. Hillary?