The problem is that the executive branch controls enforcement and the actual disbursement of money, so the other branches are really only a check to the extent that the executive branch fears dissension in the ranks or being overthrown if they ignore the law.

We say things like “no one is above the law” but that is very clearly untrue just based on the pardon power. The entire executive branch is above the law, and by design.

It’s tough, because you do need one of the branches to control enforcement, and whichever one it is, that’s really the branch that’s in charge. If you gave the legislative or the judicial branch the final say, there would be a different set of risks.