Page:Michael J. Biestek v. Nancy A. Berryhill, Acting Commissioner of Social Security.pdf/8

6 Edison, 305 U. S., at 229. See Dickinson v. Zurko, 527 U. S. 150, 153 (1999) (comparing the substantial-evidence standard to the deferential clearly-erroneous standard).

Today, Biestek argues that the testimony of a vocational expert who (like O’Callaghan) refuses a request for supporting data about job availability can never clear the substantial-evidence bar. See Brief for Petitioner 21–34. As that formulation makes clear, Biestek’s proposed rule is categorical, rendering expert testimony insufficient to sustain an ALJ’s factfinding whenever such a refusal has occurred. But Biestek hastens to add two caveats. The first is to clarify what the rule is not, the second to stress where its limits lie.

Biestek initially takes pains—and understandably so—to distinguish his argument from a procedural claim. Reply Brief 12–14. At no stage in this litigation, Biestek says, has he ever espoused “a free-standing procedural rule under which a vocational expert would always have to produce [her underlying data] upon request.” Id., at 2. That kind of rule exists in federal court: There, an expert witness must produce all data she has considered in reaching her conclusions. See Fed. Rule Civ. Proc. 26(a)(2)(B). But as Biestek appreciates, no similar requirement applies