Although perhaps oversimplifying for analysis, I think Auer deference functions like Chevron deference but one step removed from the statutory text.
- Chevron deference applies to some reasonable agency interpretations of ambiguous statutory text.
- Auer deference applies to reasonable agency subregulatory interpretations of ambiguous agency regulations (which for this purpose may be either (i) ambiguous legislative regulations (e.g., in a tax context, ambiguous consolidated return regulations) or (ii) ambiguous interpretive regulations entitled to Chevron deference (e.g., in a tax context, say ambiguous “away from home” interpretive regulations entitled to deference as in Correll)).
I don't want to get into the Justices competing views of Auer deference. The pundits will be doing that for some time now.
I do want to get into what, if anything, Kisor says about the legislative / interpretive issue that I have fulminated about recently. See Article on the Continued Viability of the APA Category of Interpretive Regulations (Federal Tax Procedure Blog 6/21/19), here; and Supreme Court Again Weighs In At the Edges on Legislative and Interpretive Rules (Federal Tax Procedure Blog 6/23/19), here.
Just to restate the issue. Some, a considerable consensus in the scholarly community, claim that the interpretive regulation is no longer viable, having been conflated into legislative rules by judicial opinions after the adoption of the APA. I reject that notion. I do note as an important pushback Justice Breyer's comment in the Kisor oral argument: “there are hundreds of thousands, possibly millions of interpretive regulations.” Justice Breyer is, of course, an administrative law expert (he and Justice Kagan are the administrative law experts on the Court), and he thinks that interpretive regulations are still viable. (Significantly, at oral argument, no Justice challenged the notion that interpretive regulations were a viable APA category.)
The Kisor opinions, as I said, were fractured, with some key points not gathering a majority. The Justices in the plurality for the Court opinion which I discuss herein were Justices Kagan (author), Ginsburg, Breyer and Sotomayor. Remember that Justices Kagan and Breyer are the Court's administrative law experts, so from the perspective I focus on (the APA distinction between legislative and interpretive regulations), Justice Kagan's opinion concurred in by Justice Breyer are most important to the legislative /interpretive issue.