Sotomayor, J., dissenting
standably asked for more details, the expert said only that she got the numbers from a publicly available source as well as from her “own individual labor market surveys” that were part of confidential client files. Id., at 71; see id., at 67, 7172. Biestek’s counsel asked if the names in the files could be redacted, but the administrative law judge (ALJ) interrupted and ruled that she would not require the surveys to be produced in redacted form. Id., at 72; see also id., at 67.
Perhaps the ALJ would have allowed Biestek’s counsel to ask followup questions about the basis for the testimony at that point, and perhaps Biestek’s counsel should have tried to do so. But a Social Security proceeding is “inquisitorial rather than adversarial.” Sims v. Apfel, 530 U. S. 103, 110–111 (2000); see 20 CFR §§404.900(b), 416.1400(b). The ALJ acts as “an examiner charged with developing the facts,” Richardson v. Perales, 402 U. S. 389, 410 (1971), and has a duty to “develop the arguments both for and against granting benefits,” Sims, 530 U. S., at 111; see also Social Security Ruling, SSR 00–4P, 65 Fed. Reg. 75760 (2000) (noting “the adjudicator’s duty to fully develop the record”). Here, instead of taking steps to ensure that the claimant had a basis from which effective cross-examination could be made and thus the record could be developed, the ALJ cut off that process by intervening when Biestek’s counsel asked about the possibility of redaction.
The result was that the expert offered no detail whatsoever on the basis for her testimony. She did not say whom she had surveyed, how many surveys she had conducted, or what information she had gathered, nor did she offer any other explanation of the data on which she relied. In conjunction with the failure to proffer the surveys themselves, the expert’s conclusory testimony alone could not constitute substantial evidence to support the ALJ’s fact-
