But the principle invoked in this case, non-delegation doctrine, is far reaching. The non-delegation doctrine is a theory, some might say a legal fiction, that says that Congress can’t delegate its power to make the laws, but can make a broad law and allow agencies can fill in details so long as Congress gives the agencies “an intelligible principle” for doing so.
This is not without basis—there is no obvious line to be drawn between Congress’s power to make laws, and the executive branch’s power to enforce them in a discretionary manner. There is nothing wrong with Congress making a broad law “fraud shall be illegal” and the SEC making rules for itself about how to enforce that. But clearly at some point executive regulation looks more like law making and less like an agency imposing guidelines for the exercise of its own discretion.
Historically the Supreme Court has been unwilling to police that line, but that could change. One thing I think you might see is greater scrutiny of agencies applying existing authority to enter new areas of regulation. The theory might be, for example, that it’s fine for the EPA to cut sulfur particulate targets, which clearly falls under the scope of the Clean Air Act, but that the agency needs new Congressional authority to do something like impose limitations on CO2 emissions, which involves a different problem than the Clean Air Act was intended to solve. There is already precedent in this direction, under something called the Major Questions Doctrine: https://crsreports.congress.gov/product/pdf/IF/IF12077
