QuoteThe Administrative Procedure Act (APA) is a federal act that governs the procedures of administrative law. The APA is codified in 5 U.S.C. §§ 551–559.

The core pieces of the act establish how federal administrative agencies make rules and how they adjudicate administrative litigation. 5 U.S.C. § 551(5)–(7) clarifies that rulemaking is the "agency process for formulating, amending, or repealing a rule," and adjudication is the final disposition of an agency matter other than rulemaking. That is, rulemaking goes beyond resolution of specific controversies between parties and includes management and administrative functions. Rulemaking and adjudication can be formal or informal, which in turn determines which APA procedural requirements apply.

https://www.law.cornell.edu/wex/administrative_procedure_act

QuoteThe case against delegation rests on the proposition that the Constitution, in the first sentence of Article I, gives "[a]ll legislative Powers" to Congress. One would therefore assume that sensitivity to delegation would be at its height when the President or some regulatory agency claims the power to issue so-called "legislative rules"—regulations that have a force and effect similar to that of a statute. At one time, the courts were very cautious about such delegations, and said they would refuse to recognize agency rules having the force of law unless they were explicitly authorized by Congress.

More recently, however, the Court has adopted something of the opposite presumption: that any statute that mentions "rules" or "regulations"—even if this could plausibly mean housekeeping or procedural rules—also includes the authority to issue legislative regulations, that is, rules that are functionally equivalent to mini-statutes. This newer presumption, which has never been justified by the Court in any considered decision, has the effect of permitting the transfer of lawmaking authority from Congress (whether this was intended or not) to administrative actors and the President.

https://reason.com/volokh/2026/03/04/the-role-of-delegation-theories-in-deforming-the-constitution/