The way the US political system works is that the legislative passes laws, the executive enforces laws, and the judicial interprets laws and ensures the constitutionality/legality of it all. This is relevant because in this scenario each body plays a critical role, but they 'beat' each other in different ways, almost like a game of rock, paper, scissors. The executive beats the legislative by vetoing laws, the judicial beats the executive by blocking/halting orders/enforcements of laws, and the legislative can beat the judiciary by passing new laws or even changing the constitution (though there you'd also need the states' approval).

This simplifies some things (like the fact that congress can beat the executive by overriding a veto), but I think generally captures the essence of the system. And a key point here is that judicial beats executive. The executive can interpret a law however they want, but if the judiciary disagrees then the judiciary wins. So nothing needs to be "used" to disregard the judiciary's interpretation of laws - it simply doesn't matter what the executive's interpretation of a law - that's the role of the judiciary.

The reason for this law is simply to bring the various agencies under executive authority in line. Instead of each individual organization interpreting the law (generally around the limits of their powers) at their own discretion, those interpretations will now need to pass through the attorney general.