PUBLISHED

UNITED STATES COURT OF APPEALS
                FOR THE FOURTH CIRCUIT


TYRONE WALLS,                           
                  Plaintiff-Appellee,
                v.
                                              No. 01-2459
JO ANNE B. BARNHART,
Commissioner of Social Security,
              Defendant-Appellant.
                                        
          Appeal from the United States District Court
           for the District of Maryland, at Baltimore.
              Jillyn K. Schulze, Magistrate Judge.
                       (CA-00-3375-JFM)

                      Argued: May 9, 2002

                     Decided: July 15, 2002

       Before TRAXLER, Circuit Judge, C. Arlen BEAM,
    Senior Circuit Judge of the United States Court of Appeals
         for the Eighth Circuit, sitting by designation, and
      Robert E. PAYNE, United States District Judge for the
        Eastern District of Virginia, sitting by designation.



Affirmed by published opinion. Senior Judge Beam wrote the opin-
ion, in which Judge Traxler and Judge Payne joined.


                            COUNSEL

ARGUED: Kathleen Anne Kane, Appellate Staff, Civil Division,
UNITED STATES DEPARTMENT OF JUSTICE, Washington,
2                         WALLS v. BARNHART
D.C., for Appellant. Dennis E. Wasitis, LAW OFFICE OF JOAN A.
BIRMINGHAM, Baltimore, Maryland, for Appellee. ON BRIEF:
Robert D. McCallum, Assistant Attorney General, Thomas M.
DiBiagio, United States Attorney, John C. Hoyle, Appellate Staff,
Civil Division, UNITED STATES DEPARTMENT OF JUSTICE,
Washington, D.C., for Appellant. Joan A. Birmingham, LAW
OFFICE OF JOAN A. BIRMINGHAM, Baltimore, Maryland, for
Appellee.


                               OPINION

BEAM, Senior Circuit Judge:

   The Commissioner of Social Security (Commissioner) appeals the
order of the magistrate judge1 vacating and remanding the administra-
tive law judge’s (ALJ) decision to uphold the Commissioner’s denial
of benefits to Tyrone Walls. The Commissioner contends that the dis-
trict court would require her to support her decision with a greater
measure of proof than that mandated by statute. We agree and affirm
the Commissioner’s final order.

                                    I.

   After the Commissioner denied Walls’ claim for disability benefits,
Walls requested a hearing before the ALJ. The ALJ determined that
Walls has the severe impairment of Crohn’s disease, and that his con-
dition requires that he be able to sit or stand at his option during a
period of time equivalent to a full-time work shift. The ALJ ulti-
mately found, based on the testimony of a vocational expert (VE),
that there are a significant number of jobs in the national economy
that Walls can perform. Accordingly, the ALJ concluded that Walls
is not disabled within the meaning of the Social Security Act (the
Act). The Appeals Council denied Walls’ request for review, thus
making the ALJ’s determination the final decision of the Commis-
sioner. Walls sought review of the final decision denying his claim,
    1
   Pursuant to 28 U.S.C. § 636(c), the parties consented to final district
court disposition by the assigned magistrate judge.
                          WALLS v. BARNHART                              3
and both he and the Commissioner moved for summary judgment.
Determining that the VE’s testimony lacked sufficient clarity to sup-
port a finding that Walls can work despite his need to sit or stand at
his option, the district court denied both motions for summary judg-
ment and remanded the matter for further consideration.2 The Com-
missioner now appeals that decision.

                                    II.

   Social Security Ruling (SSR or Ruling) 83-12 recognizes that
"[u]nskilled types of jobs are particularly structured so that a person
cannot ordinarily sit or stand at will." Therefore, "[i]n cases of
unusual limitation of ability to sit or stand, a [VE] should be con-
sulted to clarify the implications for the occupational base." SSR 83-
12.

   Determination of eligibility for social security benefits involves a
five-step inquiry. Mastro v. Apfel, 

, 177 (4th Cir. 2001).
At step five, the agency has the burden of providing evidence of a sig-
nificant number of jobs in the national economy that a claimant could
perform. Powers v. Apfel, 

, 436 (7th Cir. 2000) (citing
Bowen v. Yuckert, 

, 146 n.5 (1987)).
  2
   Ordinarily, under 28 U.S.C. § 1291 denial of a motion for summary
judgment by the district court constitutes a tentative, nonfinal and nonap-
pealable decision. Group Health Inc. v. Blue Cross Ass’n, 

,
496 (2d Cir. 1986). However, in social security cases, we often use sum-
mary judgment as a procedural means to place the district court in posi-
tion to fulfill its appellate function, not as a device to avoid nontriable
issues under usual Federal Rule of Civil Procedure 56 standards. Vaile
v. Chater, 

, 823 n.2 (N.D. Ill. 1996) (citing Hamilton
v. Sec’y of Health and Human Servs., 

, 1501 (10th Cir.
1992)). In this case, the denial of summary judgment accompanied by a
remand to the Commissioner results in a judgment under sentence four
of 42 U.S.C. § 405(g), which is immediately appealable. Sullivan v. Fin-
kelstein, 

, 625 (1990). But cf. Harper v. Bowen, 

, 680 (4th Cir. 1988) (finding that although under certain circum-
stances a remand order may be appealable, "several factors" in the case
"militate[d] against appellate review"). Accordingly, we have jurisdiction
pursuant to 28 U.S.C. § 1291.
4                          WALLS v. BARNHART
   The ALJ’s findings "as to any fact, if supported by substantial evi-
dence, shall be conclusive." 42 U.S.C. § 405(g). Consequently, judi-
cial review, either by this court or the district court, of a final decision
regarding disability benefits is limited to determining whether the
findings are supported by substantial evidence and whether the cor-
rect law was applied. Hays v. Sullivan, 

, 1456 (4th Cir.
1990); Preston v. Heckler, 

, 990 (4th Cir. 1985). In
assessing whether there is substantial evidence, the reviewing court
should not "‘undertake to re-weigh conflicting evidence, make credi-
bility determinations, or substitute [its] judgment for that of’" the
agency. 

(citation omitted) (alteration in origi-
nal).

   In the matter before us, at step five of his analysis, the ALJ set
forth five hypothetical scenarios, en masse, and asked the VE to
address them. Included was the ALJ’s directive to the VE that "[i]n
hypothetical number 3, [the ALJ would] like [the VE] to make it more
restrictive in the sense of providing for no prolong[ed] walking and
standing but with . . . the allowance for a . . . sit, stand option at the
claimant’s discretion." After the ALJ completed his list of hypotheti-
cals, the VE responded that "in hypothetical number 3," he would
eliminate all medium jobs, reduce the light jobs by fifty percent, and
include all sedentary jobs.

   The ALJ made no specific findings regarding the effect of the
sit/stand provision. He did, however, adopt the VE’s calculations of
the number of jobs in the local and national economies, which
included the reductions prompted by "hypothetical number 3." The
ALJ concluded that the Commissioner had satisfied her burden at step
five in that Walls could perform "‘other work’ identified by the
impartial vocational expert at the light and . . . sedentary exertional
levels."

   In evaluating the ALJ’s findings regarding step five, the district
court found a contradiction between the VE’s testimony and SSR 83-
12’s reference to the difficulty of finding unskilled jobs that allow a
sit/stand option. The court reasoned that the VE’s testimony that
Walls could perform certain unskilled light or sedentary jobs "contra-
dicts, or at least creates an exception to, [SSR 83-12’s] statement that
[unskilled light or sedentary] jobs are ‘particularly structured’ to pre-
                          WALLS v. BARNHART                             5
clude [the sit/stand] option." Consequently, the court found it neces-
sary to determine "what is the necessary content of, and level of
scrutiny to be applied to, contradictory VE testimony."

    The court found pertinent case law to be lacking and looked to the
Seventh Circuit’s decision in Powers for guidance. In Powers, the
court found that the VE’s testimony provided substantial evidence to
support the hearing officer’s finding that a number of jobs matching
the claimant’s need for a sit/stand option existed in the 

. The claimant had contended that it was unclear
whether the expert’s testimony as to the number of jobs available in
the economy included a sit/stand option and matched the claimant’s
skill level. 

The Seventh Circuit responded that "[t]o argue
. . . that the expert’s testimony was ‘unclear’ ignores the express limi-
tation in the hearing officer’s questions to the expert that clearly
stated the conditions under which the opinion was to be expressed."

present case, the court distinguished the result in Powers, but
simultaneously relied upon the Seventh Circuit’s reasoning, pointing
out that in Powers, the court deemed the VE testimony sufficient only
after noting "that the VE testimony was given in response to a hypo-
thetical ‘asked expressly,’ with ‘clearly stated . . . conditions.’" Walls
v. Barnhart, No. JFM 00-3375, mem. op. at 6 (D. Md. Oct. 4, 2001)
(quoting 

). The court went on to state that
"[t]here is good reason to require special clarity when a VE testifies
that a person who needs a sit/stand option can perform unskilled light
or sedentary jobs. The testimony contradicts, or at least creates an
exception to, the Ruling’s statement that such jobs are ‘particularly
structured’ to preclude that option."

  "Special clarity" is not called for by the Act. 42 U.S.C. § 405(g).
A special clarity criterion would require the agency to support its
decisions by more than the statutorily designated substantial evidence
burden. As such, the district court applied an improper standard. See

.

   There may be situations where inconsistencies within the agency
call the VE’s credibility into question and thus require remand. See
Young v. Sec’y of Health & Human Servs., 

, 392-94 (7th
6                         WALLS v. BARNHART
Cir. 1992) (concluding that the agency failed to provide sufficient
articulation for reviewing court to determine whether substantial evi-
dence supported the ALJ who had relied on the VE’s testimony when
Social Security Appeals Council had made findings at another step of
eligibility determination contrary to those of the VE, thus raising
questions about the VE’s general credibility). Indeed, this circuit
requires remand when an ALJ has relied on improper VE testimony.
English v. Shalala, 

, 1084-85 (4th Cir. 1993); see also

, 392 (indicating that, although an ALJ’s credi-
bility determinations are entitled to considerable weight, a VE’s obvi-
ous lack of credibility detracts from the weight of the evidence). Still,
no extra-statutory standard of clarity has been established and the
measure remains one of substantial evidence.

   Furthermore, in this case, there is no contradiction between SSR
83-12 and the ALJ’s findings regarding Walls’ ability to perform a
significant number of jobs in the national economy. The Ruling
acknowledges that there are jobs that allow sit/stand options. It directs
the agency to consult with a VE to assess the impact of that option
on the occupation base. The Ruling does not prescribe a formula for
assessing what jobs are available, and the VE’s inclusion of sedentary
jobs does not mean he disregarded SSR 83-12’s recognition that a
sit/stand option negatively impacts the number of unskilled jobs avail-
able.

   Nevertheless, even if this case called for some sort of heightened
clarity, it would have been satisfied. Although the ALJ presented the
various hypotheticals in a somewhat amalgamated approach, it is
clear that the VE knew he was responding to the ALJ’s instruction to
provide for no prolonged walking and standing and allow for a
sit/stand option at the claimant’s discretion. The VE specified that he
was reacting to hypothetical three, the hypothetical containing the
sit/stand option, when he eliminated all medium jobs, reduced the
light jobs by fifty percent, and kept all sedentary jobs.

                                  III.

   The ALJ consulted with a VE about the implications of the
sit/stand option on the occupational base and the VE adjusted certain
job categories accordingly and left one unchanged, thus indicating
                         WALLS v. BARNHART                          7
that he responded to the ALJ’s directive concerning the option. The
ALJ was entitled to rely on the VE’s calculations. We therefore affirm
the Commissioner’s final order.

                                                         AFFIRMED