Opinion of the Court
refusal to a request for that data—make a vocational expert’s testimony categorically inadequate? Assume that an applicant challenges our hypothetical expert to turn over her supporting data; and assume the expert declines because the data reveals private information about her clients and making careful redactions will take a fair bit of time. Nothing in the expert’s refusal changes her testimony (as described above) about job availability. Nor does it alter any other material in the record. So if our expert’s opinion was sufficient—i. e., qualified as substantial evidence—before the refusal, it is hard to see why the opinion has to be insufficient afterward.
Biestek suggests two reasons for that non-obvious result. First, he contends that the expert’s rejection of a request for backup data necessarily “cast[s her testimony] into doubt.” Reply Brief 16. And second, he avers that the refusal inevitably “deprives an applicant of the material necessary for an effective cross-examination.” Id., at 2. But Biestek states his arguments too broadly—and the nuggets of truth they contain cannot justify his proposed flat rule.
Consider Biestek’s claim about how an expert’s refusal undercuts her credibility. Biestek here invokes the established idea of an “adverse inference:” If an expert declines to back up her testimony with information in her control, then the factfinder has a reason to think she is hiding something. See id., at 16 (citing cases). We do not dispute that possibility—but the inference is far from always required. If an ALJ has no other reason to trust the expert, or finds her testimony iffy on its face, her refusal of the applicant’s demand for supporting data may properly tip the scales against her opinion. (Indeed, more can be said: Even if the applicant makes no demand, such an expert’s withholding of data may count against her.) But if (as in our prior hypothetical example, see supra, at 7–8) the ALJ views the expert and her testimony as otherwise
