Once an agency jumps through all the necessary hoops to promulgate a legally valid rule, the rule is consistent with the statute, or at least not so inconsistent with the statute, that a court will strike it down, the agency has used all of the necessary procedures, the agency has explained why it adopted the rule, it's written the essay the courts demand that it write - valid rule. Once out there, that rule functions legally exactly like a Congressional statute. If there are criminal penalties attached, violation of the rule can trigger criminal penalties. It can result in civil penalties, sometimes fines of $1 million a day in cases of some of the environmental regulations. Those agency rules can preempt state laws. Laws enacted by state legislatures inconsistent with federal agency rules, fall just as those state laws fall before congressional statutes in the event of conflict. If agencies make law through adjudicatory decisions, rather than rules, those adjudicatory decisions can have what we call res judicata effect in federal court, just like other court decisions can. That is matters that are necessarily resolved by the agency and its adjudication, those can't be argued again, even if you move from the agency, executive officials, to a court, Article 3 judges. Valid agency rules, valid agency orders have the same legal effect as things that come out of Article 1 Institution of Congress, the Article 3 Institution of the Courts. A great deal turns on what it takes for administrative agencies to jump through all of the necessary hoops to get these rules and orders out there. That's why we have long courses on administrative law. These things matter.