Does the APA support national injunctions?
Sometimes the question is asked whether the Administrative Procedure Act authorizes courts to give national injunctions, because it says that a "reviewing court shall . . . hold unlawful and set aside agency action, findings, and conclusions found to be . . . arbitrary . . ." (5 USC § 706). In this post I'll offer a quick reminder of why the APA does not authorize national injunctions.
First, when the APA was enacted the expectation was that agencies would make policy primarily through adjudication, not through general rulemaking. The leading source for this is Reuel Schiller's excellent article "Rulemaking's Promise: Administrative Law and Legal Culture in the 1960s and 1970s."
Second, "set aside" was a technical term for reversing judgments. This can be seen in Morgan v. Daniels, 153 U.S. 120, 124 (1894). This understanding is also consistent with statutes that appear to treat "enjoin" and "set aside" as distinct actions, such as 28 USC § 2112(a). Note that the case so far is cumulative: "set aside" as a term for reversing judgments, not for giving national injunctions, is exactly what we would expect if Congress were anticipating a norm of agency policymaking through adjudication.
Third, it would be very odd to think "set aside" means "enjoin enforcement of against anyone" given the full set of objects for the verb in Section 706. Those objects are: "agency action, findings, and conclusions." Findings and conclusions are not enjoined. But they may very well be set aside by a reviewing court. At this point the idea that the APA authorizes or even requires national injunctions hangs by a thread—one has to postulate a statutory zeugma. As wonderful as a good zeugma is—and who doesn't love a good zeugma?—it seems like a strained reading.
Fourth, the complete absence of national injunctions in the decades before and after the APA makes it highly unlikely that the text was understood by Congress to authorize or require national injunctions. (For evidence, see "Multiple Chancellors: Reforming the National Injunction.")
So, there are two options. You could think that Congress, never having seen a national injunction and not expecting a lot of agency rulemaking, decided it would authorize national injunctions through an idiosyncratic use of a technical term ("set aside") embedded in an extremely rare figure of speech (zeugma) but no one understood this was happening until the 1960s. Or you could think that the APA does not authorize national injunctions.