                              In the

    United States Court of Appeals
                For the Seventh Circuit
                    ____________________
No. 18‐1100
JOSEPH KRELL,
                                                 Plaintiff‐Appellee,
                                v.

ANDREW M. SAUL,
Commissioner of Social Security,
                                             Defendant‐Appellant.
                    ____________________

            Appeal from the United States District Court
                for the Eastern District of Wisconsin.
        No. 2:16‐cv‐00951 — Nancy Joseph, Magistrate Judge.
                    ____________________

    ARGUED SEPTEMBER 26, 2018 — DECIDED JULY 24, 2019
                ____________________

   Before EASTERBROOK, ROVNER, and ST. EVE, Circuit Judges.
   ST. EVE, Circuit Judge. We focus here on an issue involving
a well‐known figure in Social Security cases: the vocational
expert. Specifically, we address whether an administrative
law judge (ALJ) can decline to issue a subpoena requiring a
vocational expert to produce his underlying data sources.
Given recent Supreme Court precedent, we conclude that,
here, the ALJ did not abuse his discretion by denying a
2                                                     No. 18‐1100

request to issue such a subpoena. See Biestek v. Berryhill, 139 S.
Ct. 1148 (2019).
                         I. Background
A. The Relevant Framework
    A person suffering from a disability that renders him un‐
able to work may apply to the Social Security Administration
for disability benefits. If a claimant’s application is denied in‐
itially and on reconsideration, he may request a hearing be‐
fore an ALJ. See 42 U.S.C. § 405(b)(1); see also Smith v. Berryhill,
139 S. Ct. 1765, 1772 (2019). The ALJ is responsible for con‐
ducting a five‐step sequential evaluation process. Step one is
to determine whether the claimant is currently engaging in
gainful employment. At steps two and three, the ALJ consid‐
ers the severity of the disability. At step four, the ALJ deter‐
mines what the claimant’s disability leaves him able to do, i.e.,
his residual functional capacity, and whether given that ca‐
pacity he may still perform his past work. And last, at step
five, the ALJ assesses the claimant’s residual functional capac‐
ity, age, education, and work experience to determine
whether the claimant can perform work that is available in
significant numbers in the national economy. 20 C.F.R.
§ 404.1520; Briscoe ex rel. Taylor v. Barnhart, 425 F.3d 345, 352
(7th Cir. 2005).
    The final step is the crucial one in this case. It is also the
only step for which the Administration bears the burden of
proof. Liskowitz v. Astrue, 559 F.3d 736, 743 (7th Cir. 2009). To
assess a claimant’s ability to continue working, the ALJ often
relies on the testimony of vocational experts. See Weatherbee v.
Astrue, 649 F.3d 565, 569 (7th Cir. 2011). Vocational experts
must have specialized and current knowledge of “working
No. 18‐1100                                                       3

conditions and physical demands of various jobs; … the exist‐
ence and numbers of those jobs in the national economy; and
involvement in or knowledge of placing adult workers with
disabilities into jobs.” Biestek, 139 S. Ct. at 1152 (internal quo‐
tation marks omitted); see also Chavez v. Berryhill, 895 F.3d 962,
964 (7th Cir. 2018), cert. denied, 139 S. Ct. 808 (2019). In provid‐
ing assessments, vocational experts may rely on publicly
available sources as well as data developed through their own
experiences and research. See Biestek, 139 S. Ct. at 1152 (citing
Social Security Ruling, SSR 00–4p, 65 Fed. Reg. 75760 (2000)).
B. Joseph Krell’s Application
    Joseph Krell, a former ironworker in Wisconsin, applied
for disability benefits due to problems with his knee. His ap‐
plication was denied initially and on reconsideration. He then
requested a hearing before an ALJ.
    In October 2014, Krell was notified that the ALJ had sched‐
uled his hearing in December 2014. The notice stated that a
vocational expert would testify at the hearing. It also stated
that Krell had the right to request a subpoena for documents
or testimony “that you reasonably need to present your case
fully.” If Krell wished to obtain a subpoena, he could write to
the ALJ and describe:
      “What documents you need and/or who the wit‐
       nesses are;
      The location of the documents or witnesses;
      The important facts you expect the document or
       witness to prove; and
      Why you cannot prove these facts without a sub‐
       poena.”
4                                                    No. 18‐1100

See also 20 C.F.R. § 404.950(d) (describing how to obtain a sub‐
poena).
    Before the hearing, Krell’s counsel wrote to the ALJ re‐
questing a subpoena that would require the vocational expert
to produce at the hearing “certain documents upon which the
expert may rely in forming opinions during the course of the
hearing.” The requested documents were extensive and in‐
cluded statistics, reports, surveys, summaries, work product,
and more. Counsel also requested a description of the meth‐
odologies used by publishers or compilers of the statistics
upon which the expert planned to rely. Counsel noted that he
could not adequately cross‐examine the vocational expert if
the expert did not bring these materials to the hearing.
Among other objections, counsel objected to the expert testi‐
fying without producing reliable supporting data, and asked
that the ALJ notify him in advance of the hearing if he be‐
lieved the request was overbroad or burdensome. The ALJ
did not respond to the subpoena request before the hearing.
    At the hearing, the ALJ denied the subpoena request, rea‐
soning that the request was deficient because it had not spec‐
ified what the documents would show and why these facts
could not be shown without a subpoena. See 20 C.F.R.
§ 404.950(d). Counsel reiterated that he needed the materials
the vocational expert would rely on at the hearing so that he
could adequately cross‐examine the expert about them. The
ALJ told counsel that if he took issue with the vocational ex‐
pert’s testimony, he could challenge it on a post‐hearing basis.
    The ALJ proceeded with the hearing, allowing the voca‐
tional expert to testify by phone. The ALJ provided the expert
with a hypothetical residual functional capacity mirroring his
assessment of Krell’s abilities. In response, the expert testified
No. 18‐1100                                                  5

that Krell could work as a mail clerk, unskilled inspector, or
retail clerk, per the Dictionary of Occupational Titles. In the
expert’s estimation, these positions together made up 73,000
jobs in Wisconsin.
   During cross‐examination, the vocational expert stated
that to determine available job numbers, he relied on the oc‐
cupational projections for the state of Wisconsin, produced by
the Department of Workforce Development in 2014. Counsel
asked that the expert provide page numbers and codes for the
Wisconsin projections, which the expert did for the mail clerk
position. When he did not immediately find this information
for the inspector position, counsel responded “Okay” and
ended his cross‐examination. Despite the ALJ’s invitation to
do so, Krell made no post‐hearing submission challenging the
expert’s testimony.
   The ALJ issued a partially favorable decision, finding that
Krell was disabled and entitled to benefits, but only as of
March 2014 (due to his advancing age), rather than July 2011,
as Krell had claimed. Based on the vocational expert’s testi‐
mony, the ALJ concluded that up to March 2014, Krell was
able to perform work existing in significant numbers in the
national economy. The ALJ noted that the expert was “thor‐
oughly examine[d]” and “unimpeached.”
   The Social Security Appeals Council denied review, end‐
ing Krell’s pathway within the Administration. Krell then
successfully appealed to the district court, with a magistrate
judge presiding by consent. Krell’s subpoena request, the
magistrate judge explained, had stated what facts the re‐
quested documents would show. And although the request
had not stated expressly why a subpoena was necessary, it
was clear that counsel could not adequately cross‐examine
6                                                    No. 18‐1100

the vocational expert without prior access to his underlying
sources. Therefore, the magistrate judge concluded that the
ALJ had erred in denying Krell’s request for a subpoena.
    The Commissioner appeals.
                         II. Discussion
    The only issue before us is whether the ALJ erred in deny‐
ing Krell’s prehearing subpoena request. We review the mag‐
istrate judge’s determination de novo. Cullinan v. Berryhill, 878
F.3d 598, 603 (7th Cir. 2017). We review the ALJ’s denial of the
subpoena request for an abuse of discretion. See, e.g., Barrett v.
Berryhill, 906 F.3d 340, 345 (5th Cir. 2018); Passmore v. Astrue,
533 F.3d 658, 665 (8th Cir. 2008).
    While this case was pending, the Supreme Court held in
Biestek that a vocational expert is not categorically required to
produce his supporting data. 139 S. Ct. at 1156–57. Instead,
the factfinder should evaluate the vocational expert’s testi‐
mony, including his failure to produce the data, and deter‐
mine whether the testimony is reliable. If an ALJ, for example,
finds an expert trustworthy and believes he has good reason
to withhold underlying sources—the sources might include
private information or take significant time to compile, for ex‐
ample—the failure to produce such sources “need not make a
difference.” Id. at 1156. In other cases, “the refusal to disclose
data, considered along with other shortcomings, will prevent
a court from finding that a reasonable mind could accept the
expert’s testimony.” Id. at 1156 (internal quotation marks
omitted). Although an expert’s refusal to provide his sources
may interfere with the claimant’s cross‐examination of the ex‐
pert, “an ALJ and reviewing court may properly consider
No. 18‐1100                                                                7

obstacles to such questioning when deciding how much to
credit an expert’s opinion.” Id. at 1156.
    Turning to Krell’s case, it is within an ALJ’s discretion to
issue a prehearing subpoena. He may do so when the sub‐
poena is “reasonably necessary for the full presentation of a
case” and when certain “facts could not be proven without
issuing a subpoena.” 20 C.F.R. § 404.950(d).
    We agree with Krell and the magistrate judge that the sub‐
poena request did state why Krell thought the requested doc‐
uments were important and that Krell believed he needed
them to “adequately cross examine” the vocational expert.
But that Krell alleged that a subpoena was necessary did not
automatically make it so. See Butera v. Apfel, 173 F.3d 1049,
1058–59 (7th Cir. 1999). At the hearing, the ALJ pointed out
that, despite Krell’s assertion, Krell had not in fact shown why
it was necessary for the expert to produce his sources, a pre‐
requisite to obtaining a subpoena. Why, the ALJ asked,
couldn’t counsel just question the expert about his sources at
the hearing? And if Krell wanted to challenge the expert’s re‐
liance on those sources, why couldn’t he do so post‐hearing?
These questions, it turns out, were spot on.
   We keep in mind here that Krell’s argument is that the ALJ
erred in denying the subpoena request, requiring reversal. He
has not argued that, putting the subpoena request aside, the
vocational expert’s testimony did not constitute substantial
evidence.1 See Chavez, 895 F.3d at 967 (noting that, on appeal,



1
 While Krell alluded to this in his post‐Biestek position statement, the dis‐
cussion was brief and underdeveloped. Schaefer v. Universal Scaffolding &
Equip., LLC, 839 F.3d 599, 607 (7th Cir. 2016) (“Perfunctory and
8                                                   No. 18‐1100

“we ask whether substantial evidence supported the ALJ’s
conclusion”). So, we analyze only the subpoena request, not
the expert’s eventual testimony, and ask whether Krell was
entitled to require that the expert produce his underlying
sources at the hearing.
    What Krell sought to do, it seems, was to require the vo‐
cational expert to make his underlying sources available on
demand. See McKinnie v. Barnhart, 368 F.3d 907, 911 (7th Cir.
2004) (“A vocational expert is free to give a bottom line, but
the data and reasoning underlying that bottom line must be
available on demand if the claimant challenges the founda‐
tion of the vocational expertʹs opinions.”) (internal quotation
marks omitted), abrogated by Biestek, 139 S. Ct. 1148. Biestek,
however, rejects such a requirement; Biestek clearly held that
vocational experts are not categorically required to provide
their underlying data. The expert may decline to do so, and if
he does, this failure goes to the weight the ALJ may give the
testimony. Considering the totality of his testimony, the ex‐
pert can be deemed credible even if he provides no underly‐
ing data. The ALJ makes such determinations on a case‐by‐
case basis. Biestek, 139 S. Ct. at 1157.
    We acknowledge that it would be helpful to have the ex‐
pert’s underlying sources at a hearing. But, beyond arguing
for a categorical rule, which, like in Biestek, cannot be imposed
here, Krell has advanced no reason why it was necessary for
the expert to produce his underlying sources. We therefore
cannot say that the ALJ erred in denying the subpoena re‐
quest.


undeveloped arguments are waived, as are arguments unsupported by
legal authority.”).
No. 18‐1100                                                     9

    We want to be clear that our holding today and that of
Biestek do not give vocational experts carte blanche to testify
without providing underlying sources. It is certainly best
practice for vocational experts to provide underlying sources
at hearings, and we encourage them to do so. See Biestek, 139
S. Ct. at 1155 (noting that a vocational expert’s testimony
would be “more reliable and probative” and “a best practice
for the SSA and its experts” if the expert “produced support‐
ing data”); see also Social Security Administration, Vocational
Expert Handbook, 37 (Aug. 2017), https://www.ssa.gov/ap‐
peals/public_experts/Vocational_Experts_(VE)_Handbook‐
508.pdf (“You should have available, at the hearing, any vo‐
cational resource materials that you are likely to rely upon
and should be able to thoroughly explain what resource ma‐
terials you used and how you arrived at your opinions.”). We
will review on a case‐by‐case basis situations where a voca‐
tional expert does not produce his sources and the ALJ de‐
clines to require him to do so. In some cases, the vocational
expert’s testimony may prove to be unreliable without under‐
lying sources, and in those cases the testimony may neither
constitute substantial evidence nor be used as the basis for an
ALJ’s determination.
    On a final note, we have previously suggested that in cases
where underlying data may not be available at the hearing,
(say, for example, the vocational expert testified by phone, as
was the case here), the claimant should have the opportunity
to make additional argument about the data post‐hearing.
Britton v. Astrue, 521 F.3d 799, 804 (7th Cir. 2008) (per curiam).
This suggestion stems from the recognition “that the lack of
pretrial discovery in Social Security hearings can make the
task of cross‐examining a [vocational expert] quite difficult.”
Id. We have never mandated that post‐hearing challenges be
10                                               No. 18‐1100

allowed, and we decline to do so here. But nothing in Biestek
forces us to reconsider our recommendation, and we continue
to encourage ALJs to allow claimants to submit post‐hearing
argument about a vocational expert’s testimony, especially
when the underlying sources are not available during the
hearing or are not provided at all.
                      III. Conclusion
   For the foregoing reasons, we REVERSE the judgment of
the district court and AFFIRM the Commissioner’s decision.
