Court Opinion

ID: 4693975
Source: CourtListenerOpinion
Date Created: 2021-06-09 15:02:32.690823+00
Date Added: 2024-06-11T08:05:26.690595
License: Public Domain

Case: 20-2168    Document: 27     Page: 1   Filed: 06/09/2021

   United States Court of Appeals
       for the Federal Circuit
                  ______________________

                  JOSEPH J. SNYDER,
                   Claimant-Appellant

                             v.

       DENIS MCDONOUGH, SECRETARY OF
              VETERANS AFFAIRS,
               Respondent-Appellee
              ______________________

                        2020-2168
                  ______________________

     Appeal from the United States Court of Appeals for
 Veterans Claims in No. 19-3918, Judge William S. Green-
 berg.
                 ______________________

                   Decided: June 9, 2021
                  ______________________

     JENNIFER ANN ZAJAC, Paralyzed Veterans of America,
 Washington, DC, argued for claimant-appellant. Also rep-
 resented by LINDA E. BLAUHUT.

     KYLE SHANE BECKRICH, Commercial Litigation Branch,
 Civil Division, United States Department of Justice, Wash-
 ington, DC, argued for respondent-appellee. Also repre-
 sented by JEFFREY B. CLARK, ELIZABETH MARIE HOSFORD,
 ROBERT EDWARD KIRSCHMAN, JR.; BRIAN D. GRIFFIN, DEREK
 SCADDEN, Office of General Counsel, United States Depart-
 ment of Veterans Affairs, Washington, DC.
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 2                                      SNYDER   v. MCDONOUGH

                   ______________________

     Before TARANTO, LINN, and CHEN, Circuit Judges.
 TARANTO, Circuit Judge.
     Joseph Snyder served in the U.S. Army for less than 50
 days in 1974—during the Vietnam era, a “period of war,”
 38 C.F.R. § 3.2(f)—his service ending with an honorable
 discharge when a knee injury rendered him unfit. Four
 decades later, he was diagnosed with Amyotrophic Lateral
 Sclerosis (ALS). He sought disability benefits for ALS from
 the Department of Veterans Affairs (VA) under 38 U.S.C.
 § 1110, which provides for compensation for service-con-
 nected disability—specifically, for “disability resulting
 from personal injury suffered or disease contracted in line
 of duty, or for aggravation of a preexisting injury suffered
 or disease contracted in line of duty, in the active military,
 naval, air, or space service, during a period of war,” subject
 to exceptions (for dishonorable discharge and willful mis-
 conduct or abuse of alcohol or drugs) inapplicable to Mr.
 Snyder. A decision of the U.S. Court of Appeals for Veter-
 ans Claims (Veterans Court) rejecting his claim for benefits
 based on ALS is before us.
     In the Veterans Court, Mr. Snyder relied, to meet the
 fundamental requirement of service connection, solely on
 an argument about a VA regulation, adopted in 2008 and
 made final in 2009, that provides a presumption of service
 connection for veterans with ALS if specified preconditions
 are satisfied. 38 C.F.R. § 3.318(a), (b). Mr. Snyder undis-
 putedly does not satisfy one of those preconditions—that
 the veteran “have active, continuous service of 90 days or
 more.” Id. § 3.318(b)(3). Nevertheless, Mr. Snyder argued
 in the Veterans Court that the 90-day-service precondition
 is unlawful, because contrary to the statutory scheme and
 arbitrary and capricious, and that the presumption should
 remain in place with the precondition nullified, entitling
 him to a finding of service connection.
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 SNYDER   v. MCDONOUGH                                        3

     The Veterans Court rejected Mr. Snyder’s contention
 that the 90-day-service precondition is unlawful. We have
 jurisdiction to review that legal conclusion. 38 U.S.C.
 § 7292(a). We decide the legal issue de novo. Bazalo v.
 West, 150 F.3d 1380, 1382 (Fed. Cir. 1998). We affirm.
                                I
     Mr. Snyder challenges the validity of a portion of 38
 C.F.R. § 3.318, which establishes a presumption of “service
 connection”—the term used for the requirement of § 1110
 and the counterpart provision for peacetime service, 38
 U.S.C. § 1131; see Walker v. Shinseki, 708 F.3d 1331, 1334
 (Fed. Cir. 2013)—for veterans who develop ALS, under cer-
 tain prescribed preconditions. Section 3.318 provides:
    (a) Except as provided in paragraph (b) of this sec-
    tion, the development of amyotrophic lateral scle-
    rosis manifested at any time after discharge or
    release from active military, naval, or air service is
    sufficient to establish service connection for that
    disease.
    (b) Service connection will not be established under
    this section:
          (1) If there is affirmative evidence that am-
          yotrophic lateral sclerosis was not incurred
          during or aggravated by active military,
          naval, or air service;
          (2) If there is affirmative evidence that am-
          yotrophic lateral sclerosis is due to the vet-
          eran’s own willful misconduct; or
          (3) If the veteran did not have active, con-
          tinuous service of 90 days or more.
 38 C.F.R. § 3.318 (emphasis added).
    This presumption is entirely a regulatory creation. Alt-
 hough Congress has enacted several provisions that
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 4                                      SNYDER   v. MCDONOUGH

 establish service-connection presumptions applicable in
 certain circumstances, see, e.g., 38 U.S.C. §§ 1112, 1116–
 1118, Congress has created no statutory presumption ap-
 plicable to ALS. The Secretary promulgated § 3.318 pur-
 suant to the general rulemaking authority granted by 38
 U.S.C. § 501(a) to “prescribe all rules and regulations
 which are necessary or appropriate to carry out the laws
 administered by the Department . . . , including . . . regula-
 tions with respect to the nature and extent of proof and ev-
 idence and the method of taking and furnishing them in
 order to establish the right to benefits under such laws.”
 The law being carried out, the Secretary specified, was the
 requirement of “service connection” stated in 38 U.S.C.
 § 1110. See Presumption of Service Connection for Amyo-
 trophic Lateral Sclerosis, 73 Fed. Reg. 54,691, 54,692 (Sept.
 23, 2008) (Interim Final Rule) (reciting § 501 authority ap-
 plied to service-connection requirement of § 1110).
      The Secretary’s proposal and adoption of the regulation
 followed receipt of a VA-commissioned report by the Na-
 tional Academy of Sciences Institute of Medicine (IOM)
 that reviewed studies of the relationship of ALS to military
 service. See Institute of Medicine, Amyotrophic Lateral
 Sclerosis in Veterans: Review of the Scientific Literature
 (Nov. 2006) (IOM Report); see also Interim Final Rule, 73
 Fed. Reg. at 54,691. The IOM Report notes that ALS is a
 neuromuscular disease that causes nerve cells in the brain
 and spinal cord to degenerate and, accordingly, is almost
 always fatal. IOM Report at 1. It also states that, although
 about 5–10% of ALS cases are inherited, the cause of the
 remaining cases is still unknown. Id. Nevertheless, the
 IOM Report states, the scientific literature indicated that
 there was “limited and suggestive evidence of an associa-
 tion between military service and later development of
 ALS.” Id. at 3; see also id. at 35 (identical language in bold
 as final conclusion of the IOM Report).
    Central to that conclusion in the IOM Report, see id. at
 32–35, is a study by M.G. Weisskopf and colleagues
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 SNYDER   v. MCDONOUGH                                       5

 published not long before the IOM Report. The Weisskopf
 study compared the incidence of ALS-related deaths among
 those with military service and those without. M.G.
 Weisskopf et al., Prospective Study of Military Service and
 Mortality from ALS, 64 Neurology (1) 32 (2005)
 (Weisskopf). The Weisskopf study analyzed a population
 (previously assembled for unrelated purposes) of 408,288
 individuals, of whom 281,874 had served in the military,
 including during World War I, World War II, the Korean
 War, or the Vietnam War. 1 Id. at 32. The study split those
 participants who had military service into equal “quin-
 tiles”—according to years of service—and calculated the
 median length of service, measured in whole-number
 years, for the participants in each quintile. See id. at 33
 (“The total number of years of service was categorized by
 quintile. . . . For total years served, this was done by as-
 signing medians to each quintile and modeling the median
 values as a continuous variable.”); id. at 34 (table showing
 “Adjusted relative risk (RR) of ALS by years of military ser-
 vice, 1989–1998,” rows for no military service and each of
 five quintiles, by “Median years”). 2 Considering factors
 like age, smoking, and alcohol intake that might have af-
 fected rates of ALS, the Weisskopf study found that the rel-
 ative risk of developing ALS was higher for those with
 military service than those without, that “[t]he increased
 risk of ALS was largely independent of the number of years
 served in the military,” and that the increased risk was
 “largely independent of the branch of military service, the
 years when service occurred, or the number of years
 served.” Id. at 34–35 (emphases added).

     1    The study’s results focused on participants’ service
 in World War II, Korea, and Vietnam; only 592 people re-
 ported service during World War I. Weisskopf at 35.
     2    The median years of service, from the first quintile
 to the fifth quintile, respectively, were: 2 years, 3 years, 4
 years, 5 years, and 9 years. Weisskopf at 34.
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 6                                     SNYDER   v. MCDONOUGH

     The 2006 IOM Report observes that, while other stud-
 ies had focused only on the Gulf War, the Weisskopf study
 was “the first to suggest a relationship between military
 service before the Gulf War and ALS mortality.” IOM Re-
 port at 34. The report notes greater limitations of the other
 studies reviewed, id. at 26–31, 35, but as to the Weisskopf
 study, it states that “overall it was a well-designed and
 well-conducted study” and that, despite “limitations inher-
 ent in an analysis of a cohort assembled for other purposes,
 the findings are intriguing.” Id. at 34. “The implication is
 that military service in general—not confined to exposures
 specific to the Gulf War—is related to the development of
 ALS.” Id. The IOM Report adds: “The findings, if validated
 in other studies, suggest that exposures during military
 service, even among those with no wartime service, might
 be responsible.” Id.
     In accordance with the conclusions of the IOM Report
 and the Weisskopf study, the Secretary proposed an in-
 terim final rule—effective immediately but subject to no-
 tice and comment before adoption as a permanent rule—
 establishing a presumption of service connection for “any
 veteran who develops [ALS] at any time after separation
 from service.” Interim Final Rule, 73 Fed. Reg. at 54,691.
 The Secretary noted the observed link between ALS and
 military service and also found that it was “unlikely that
 conclusive evidence [of the causes of ALS] will be developed
 in the foreseeable future.” Id. Given the rapidly progres-
 sive and degenerative nature of the disease, as well as “con-
 tinuing uncertainty regarding specific precipitating factors
 or events that lead to development of [ALS],” the Secretary
 determined that there would be “great difficulty” for veter-
 ans seeking benefits for ALS to prove service connection in
 the absence of the presumption. Id. at 54,692.
     After explaining the basis for adopting a presumption
 at all, the Secretary enumerated three circumstances for
 which post-military-service ALS would not suffice to estab-
 lish service connection. See id. First, service connection
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 SNYDER   v. MCDONOUGH                                     7

 would not be established “if there is affirmative evidence
 that ALS was not incurred during or aggravated by” the
 veteran’s military service—which is what justifies the “pre-
 sumption” label. Id. (emphasis added); see also 38 C.F.R.
 § 3.318(b)(1). Next, service connection would not be pre-
 sumed if, consistent with the exception in § 1110 itself,
 there is “affirmative evidence that ALS was caused by the
 veteran’s own willful misconduct.” Interim Final Rule, 73
 Fed. Reg. at 54,692; see also 38 C.F.R. § 3.318(b)(2). Fi-
 nally, and relevant here, service connection would not be
 presumed “if the veteran did not have active, continuous
 service of 90 days or more.” Interim Final Rule, 73 Fed.
 Reg. at 54,692; see also 38 C.F.R. § 3.318(b)(3).
     As to the 90-day-service precondition, the Secretary
 reasoned:
    Although the Weisskopf study relied upon by the
    IOM report concluded that veterans have an in-
    creased risk of developing ALS compared to civil-
    ians regardless of years of service, a minimum-
    service requirement of 90 days would not be incon-
    sistent with the study’s findings because the study
    focused on veterans’ “years” of service and did not
    consider minimum periods of service. We believe
    that 90 days is a reasonable period to ensure that
    an individual has had sufficient contact with activ-
    ities in military service to encounter any hazards
    that may contribute to development of ALS.
 Interim Final Rule, 73 Fed. Reg. at 54,692. The Secretary
 noted that 90-day-service requirements also apply to pre-
 sumptions of service connection for chronic and tropical
 diseases, citing 38 U.S.C. § 1112(a) and 38 C.F.R.
 § 3.307(a)(1). Id. Thus, the Secretary concluded, “Con-
 gress considered 90 days to be the minimum period neces-
 sary to support an association between such service and
 subsequent development of disease” and “for any shorter
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 8                                      SNYDER   v. MCDONOUGH

 period, it is more likely than not that ALS was not associ-
 ated with service.” Id.
     After receiving comments, the Secretary adopted the
 interim rule as a final rule, which was later adopted as
 § 3.318. See Presumption of Service Connection for Amyo-
 trophic Lateral Sclerosis, 74 Fed. Reg. 57,072, 57,072
 (Nov. 4, 2009) (Final Rule). The Secretary noted:
     The ALS Association expressed support for this
     regulation and stated its belief that 90 continuous
     days of service in the military and a diagnosis of
     ALS are sufficient to establish presumptive service
     connection for that disease. New § 3.318 generally
     establishes presumptive service connection for ALS
     if a veteran had at least 90 continuous days of ac-
     tive military, naval, or air service and developed
     ALS at any time after separation from such service.
     We made no changes based on this comment.
 Id. at 57,073.
                               II
      Under the statute conferring jurisdiction on this court
 for this case, we must “hold unlawful and set aside” regu-
 lations that are (1) arbitrary, capricious, an abuse of dis-
 cretion, or otherwise not in accordance with law; (2)
 contrary to constitutional right, power, privilege, or im-
 munity; (3) in excess of statutory jurisdiction, authority, or
 limitations, or in violation of a statutory right; or (4) with-
 out observance of procedure required by law. 38 U.S.C.
 § 7292(d)(1).    Mr. Snyder challenges the validity of
 § 3.318(b)(3)’s 90-day-service requirement, first, as exceed-
 ing the Secretary’s statutory authority and, second, as ar-
 bitrary and capricious. Snyder Opening Br. at 16–29, 29–
 39. We must reject these challenges.
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 SNYDER   v. MCDONOUGH                                      9

                              A
      In promulgating 38 C.F.R. § 3.318, the Secretary in-
 voked 38 U.S.C. § 501(a) as legal authority. We agree with
 the Secretary that § 501(a) supplies the required statutory
 authority for the regulation and that § 3.318, as an exercise
 of the § 501(a) authority to adopt conditional presumptions
 of facts required by 38 U.S.C. § 1110, is not contrary to
 other statutory provisions cited by Mr. Snyder.
     Section 501(a) grants the Secretary the authority to
 “prescribe all rules and regulations which are necessary or
 appropriate to carry out the laws administered by the De-
 partment and are consistent with those laws,” including
 “regulations with respect to the nature and extent of proof
 and evidence and the method of taking and furnishing
 them in order to establish the right to benefits under such
 laws.” 38 U.S.C. § 501(a). Section 501(a) confers “broad”
 rulemaking authority. Nat’l Org. of Veterans’ Advocates,
 Inc. (NOVA) v. Sec’y of Veterans Affairs, 669 F.3d 1340,
 1345 (Fed. Cir. 2012). Such broad authority, defined in
 general terms, encompasses particular topics that are not
 themselves expressly mentioned as long as they come
 within the generally defined grant: “A regulation does not
 contradict the statutory scheme . . . simply because it ad-
 dresses an issue on which the scheme is silent.” Lofton v.
 West, 198 F.3d 846, 850 (Fed. Cir. 1999).
     Relying on § 501(a)(1), the Secretary has issued regu-
 lations—like the one at issue here—establishing a service-
 connection presumption for certain conditions without a
 statutory scheme explicitly permitting such presumptions.
 See 38 C.F.R. § 3.307(a)(6)(iv) (establishing a service-con-
 nection presumption for veterans exposed to herbicide
 agents “in or near the Korean DMZ”); id. § 3.307(a)(6)(v)
 (same for veterans who “regularly and repeatedly operated,
 maintained, or served onboard C-123 aircraft” “during the
 Vietnam era”); id. § 3.307(a)(7) (same for diseases “associ-
 ated with exposure to contaminants in the water supply at
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 10                                     SNYDER   v. MCDONOUGH

 Camp Lejeune”); id. § 3.316 (same for diseases associated
 with “specified vesicant agents”). These presumptions, if
 otherwise supported on their merits and duly promulgated,
 come within the Secretary’s power to issue “regulations
 with respect to the nature and extent of proof and evidence”
 that will suffice “to establish the right to benefits” claimed.
 38 U.S.C. § 501(a)(1). A presumption, while not itself “evi-
 dence,” is a measure “with respect to” the evidence that is
 necessary or sufficient under an applicable statutory
 standard. A presumption “affords a party, for whose bene-
 fit the presumption runs, the luxury of not having to pro-
 duce specific evidence to establish the point at issue. When
 the predicate evidence is established that triggers the pre-
 sumption, the further evidentiary gap is filled by the pre-
 sumption.” Routen v. West, 142 F.3d 1434, 1440 (Fed. Cir.
 1998) (emphases added).
     Here, the presumption of service connection for ALS
 created by § 3.318 goes to the “nature and extent” of the
 evidence that a veteran must provide to prove service con-
 nection. A veteran with ALS need not “produce specific ev-
 idence,” id., showing that the disability “result[ed] from
 personal injury suffered or disease contracted in line of
 duty” or showing the specified “aggravation” in service, 38
 U.S.C. § 1110. Instead, if the preconditions are satisfied,
 the presumption supplies the required evidence. 3 Eviden-
 tiary rules like this one are within the Secretary’s rulemak-
 ing authority under § 501(a)(1).

      3 The Board of Veterans’ Appeals determined that
 Mr. Snyder had not made a case-specific showing of service
 connection. J.A. 17. That is hardly surprising, given that
 the causes of ALS are unknown. In the Veterans Court,
 Mr. Snyder relied solely on the regulatory presumption to-
 gether with his argument that the presumption must be
 modified to eliminate the 90-day-service precondition.
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 SNYDER   v. MCDONOUGH                                      11

      Mr. Snyder suggests that because § 3.318 distinguishes
 veterans who meet particular requirements from those
 who do not, the regulation is an unlawful modification of
 the statutory definition of “veteran” in 38 U.S.C. § 101(2).
 See Snyder Opening Br. at 23–27. That contention is mer-
 itless. Section 3.318 does not modify the definition of “vet-
 eran,” and there is no dispute that Mr. Snyder meets the
 definition. See Secretary Response Br. at 20. Nothing in
 § 101(2) requires that all veterans be subject to the same
 regulatory evidentiary requirements, no matter their cir-
 cumstances. Various regulations make evidentiary dis-
 tinctions without express statutory authorization. See,
 e.g., 38 C.F.R. § 3.307(a)(6)(iv) (presumption applies only to
 veterans who operated “in or near the Korean DMZ”); id.
 § 3.307(a)(6)(v) (presumption applies only to veterans who
 “regularly and repeatedly operated, maintained, or served
 onboard C-123 aircraft” “during the Vietnam era”); id.
 § 3.307(a)(7) (presumption applies only to veterans who
 served at Camp Lejeune).
     Mr. Snyder also points to 38 U.S.C. § 5303A to support
 his argument that the Secretary exceeded his statutory au-
 thority. See Snyder Opening Br. at 22–24. But that provi-
 sion, like § 101(2), is not inconsistent with regulations that
 make evidentiary requirements dependent on particular
 circumstances that not all veterans share. Section 5303A
 adds a general minimum-service requirement to the re-
 quirement of being a veteran for general-benefits eligibil-
 ity, 38 U.S.C. § 5303A(b)(1), (2), but defines numerous
 exceptions to that added requirement, id. § 5303A(b)(3).
 The provision does not preclude the Secretary’s regulatory
 relaxation of evidentiary requirements for service connec-
 tion for veterans having particular physical disabilities and
 also meeting specified conditions.
     We therefore reject Mr. Snyder’s argument that
 § 3.318, with its 90-day-service requirement, exceeds the
 Secretary’s statutory authority and contradicts certain
 statutory provisions. Mr. Snyder has not challenged the
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 12                                     SNYDER   v. MCDONOUGH

 procedural propriety of the promulgation of § 3.318. But
 he does argue that the rule, with its 90-day-service require-
 ment, is arbitrary and capricious. Snyder Opening Br. at
 29–39. We turn to that challenge.
                               B
     Arguing that the 90-day-service requirement is “arbi-
 trary and capricious,” Mr. Snyder contends that (1) the Sec-
 retary did not offer a reasonable justification for comparing
 ALS to chronic and tropical diseases when imposing a 90-
 day-service requirement, id. at 31–37, and (2) the
 Weisskopf study found that military service was associated
 with an increased risk of ALS regardless of time served, id.
 at 37–39. Applying the deferential standard of review re-
 quired for our assessment of this challenge, we must reject
 Mr. Snyder’s argument.
     Under 38 U.S.C. § 7292(d)(1), whose pertinent lan-
 guage is identical to that of the judicial-review provision of
 the Administrative Procedure Act (APA), 5 U.S.C.
 § 706(2)(A), we must “set aside any regulation relied on by
 the Veterans Court that is ‘arbitrary, capricious, an abuse
 of discretion, or otherwise not in accordance with law,’”
 Hansen-Sorenson v. Wilkie, 909 F.3d 1379, 1384 (Fed. Cir.
 2018) (quoting 38 U.S.C. § 7292(d)(1)). We follow the prac-
 tice of treating the first two terms in the list as forming a
 single “arbitrary-and-capricious standard.” FCC v. Prome-
 theus Radio Project, 141 S. Ct. 1150, 1158 (2021). That
 standard requires the agency’s action to “be reasonable and
 reasonably explained.” Id.
      We have recognized that “treating like cases differently
 can be arbitrary and capricious,” Hansen-Sorenson, 909
 F.3d at 1384 (emphasis added and internal quotation
 marks omitted), but whether cases are “like” is a matter
 initially for the agency, and on that question, as on other
 factual and policy questions, distinctions need not be based
 on “conclusive proof,” Carpenter, Chartered v. Sec’y of Vet-
 erans Affairs, 343 F.3d 1347, 1353 (Fed. Cir. 2003). Our
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 SNYDER   v. MCDONOUGH                                          13

 review of a regulation for compliance with the arbitrary-
 and-capricious standard is “deferential.” Prometheus Ra-
 dio Project, 141 S. Ct. at 1158. We may not “substitute
 [our] own policy judgment” for that of the Secretary. Id.;
 see also McKinney v. McDonald, 796 F.3d 1377, 1383 (Fed.
 Cir. 2015). In reviewing a challenge like Mr. Snyder’s, “[a]
 court simply ensures that the agency has acted within a
 zone of reasonableness and, in particular, has reasonably
 considered the relevant issues and reasonably explained
 the decision.” Prometheus Radio Project, 141 S. Ct. at 1158.
 Although “we may not supply a reasoned basis for the
 agency’s action that the agency itself has not given, we will
 uphold a decision of less than ideal clarity if the agency’s
 path may reasonably be discerned.” Bowman Transp., Inc.
 v. Arkansas–Best Freight Sys., Inc., 419 U.S. 281, 285–86
 (1974) (citing SEC v. Chenery Corp., 332 U.S. 194, 196
 (1947)). We conclude that § 3.318 passes muster under
 those standards.
     The Secretary set forth most of his reasoning in an-
 nouncing the Interim Final Rule. 73 Fed. Reg. at 54,691–
 92. The Secretary made clear that the question was what
 facts might justifiably support a presumption of the statu-
 torily required element that a veteran’s ALS is connected
 to “military service,” id. at 54,691, i.e., to “activities in mil-
 itary service,” id. at 54,692—more specifically, what facts
 “support a presumption that the resulting disability was
 incurred in the line of duty during active military, naval,
 or air service,” id. That focus on the needed connection to
 active military service reflects the statutory standard of 38
 U.S.C. § 1110, which the Secretary cited. Interim Final
 Rule, 73 Fed. Reg. at 54,692.
     The Secretary relied on the IOM report and particu-
 larly the IOM Report’s description of the Weisskopf study
 as providing “‘limited and suggestive evidence’” of an ALS
 association with military service, id. at 54,691, to conclude
 that “there is sufficient evidence indicating a correlation
 between ALS and activities in military service” to support
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 14                                     SNYDER   v. MCDONOUGH

 “a presumption of service connection” for veterans with
 ALS, id. at 54,691–92. The Secretary simultaneously con-
 cluded, however, that the justified presumption was condi-
 tional on a minimum period of service of 90 days. Id. at
 54,692. “[W]e believe that, for any shorter period, it is more
 likely than not that ALS was not associated with service.”
 Id.
      The Secretary’s rationale is easy to discern. First, the
 general logic is that the statutory requirement at issue is
 one of causal connection to activities in military service
 and, in the absence of evidence to the contrary, at some
 point near the de minimis end of the spectrum of service
 length, there is too little time in service for there to have
 been enough activities in service to make the causal con-
 nection likely. See id. (deeming it appropriate to adopt “a
 reasonable period to ensure that an individual has had suf-
 ficient contact with activities in military service to encoun-
 ter any hazards that may contribute to development of
 ALS”). That logic is reasoned and reasonable.
      Second, focusing on the record regarding ALS, the Sec-
 retary found no reliable evidence of a correlation between
 ALS and service of periods as short as 90 days. Specifically,
 the crucial Weisskopf “study focused on veterans’ ‘years’ of
 service and did not consider minimum periods of service.”
 Id. (emphasis added). That reading of the Weisskopf study
 is supported by the study itself, which, as quoted above,
 makes clear that time measurements were in units of
 years, not any smaller units, and which supplies no evi-
 dence of a service-ALS correlation for veterans with service
 of periods substantially shorter than a year.
     Third, the Secretary concluded that 90 days was “a rea-
 sonable period to ensure” a minimum degree of contact
 with hazards that may contribute to development of ALS.
 Id. Specifically, the Secretary observed that Congress had
 used a 90-day-service period for its presumption of service
 connection for chronic and tropical diseases. Id. (citing 38
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 SNYDER   v. MCDONOUGH                                     15

 U.S.C. § 1112(a) and its regulatory counterpart, 38 C.F.R.
 § 3.307(a)(1)). If, as we have concluded, it was reasonable
 for the Secretary to adopt some minimum period of service
 for that purpose, Mr. Snyder has not given us a basis for
 deeming it unreasonable for the Secretary to borrow the
 particular period Congress chose to achieve the same pur-
 pose for another substantial class of conditions. See 38
 U.S.C. § 1101(3), (4) (listing numerous diseases that are
 “‘chronic disease[s]’” or “‘tropical disease[s]’”).
     Mr. Snyder contends that the Secretary should have
 compared ALS to other presumptions having no minimum
 service requirements. Snyder Opening Br. at 36–37. But
 the presumptions Mr. Snyder points to, both statutory and
 regulatory, involve “exposure to a substance or set of sub-
 stances with known risks, either directly or through pres-
 ence in a particular place, such as Vietnam,” Secretary
 Response Br. at 39, or a type of circumstance (time as a
 prisoner of war) associated with specified medical condi-
 tions. 4 The ALS presumption does not: It is not known
 what causes ALS, either generally or within the range of
 activities that are part of military service. We have “no
 basis for concluding that the Secretary cannot reasonably
 distinguish the ALS situation” from situations that involve
 a “specific harm-causing chemical agent, use of specific
 equipment, or periods of time at a specific location.” Han-
 sen-Sorenson, 909 F.3d at 1384.
     There was no evidence requiring the Secretary to make
 a different choice. Mr. Snyder has not pointed to such evi-
 dence in the rulemaking record but ignored by the Secre-
 tary. In fact, in adopting the Final Rule, the Secretary

     4    These include service-connection presumptions for
 diseases associated with time spent as a prisoner of war (38
 U.S.C. § 1112(b)); exposure to radiation (id. § 1112(c)), ex-
 posure to Agent Orange in Vietnam (id. § 1116), and ser-
 vice in the Persian Gulf War (id. § 1118).
Case: 20-2168    Document: 27     Page: 16    Filed: 06/09/2021

 16                                    SNYDER   v. MCDONOUGH

 noted that the ALS Association endorsed the 90-day-ser-
 vice requirement, and Mr. Snyder has not identified any
 contrary comments that went unmentioned by the Secre-
 tary. Final Rule, 74 Fed. Reg. at 57,073. Supportive com-
 ments “in the rulemaking record” can “buttress[]” a finding
 that an agency’s regulation is reasonable. Carpenter, 343
 F.3d at 1355–56. Mr. Snyder also has not pointed to evi-
 dence that was readily available to the Secretary but not
 obtained. See CS Wind Vietnam Co. v. United States, 832
 F.3d 1367, 1380 n.7 (Fed. Cir. 2016) (recognizing that “an
 agency’s ‘failure to adduce empirical data that can readily
 be obtained’ can sometimes require setting aside an
 agency’s decision” under the APA (citing FCC v. Fox Tele-
 vision Stations, Inc., 556 U.S. 502, 519 (2009))). Indeed,
 the Secretary expressly “welcome[d] comments on any rel-
 evant peer-reviewed literature concerning ALS that ha[d]
 been published since the November 2006 IOM report.” In-
 terim Final Rule, 73 Fed. Reg. at 54,692. And the Secre-
 tary was under “no general obligation . . . to conduct or
 commission [his] own empirical or statistical studies.” Pro-
 metheus Radio Project, 141 S. Ct. at 1160.
     In these circumstances, neither the evidence nor logic
 required the Secretary to limit his options to either ignor-
 ing length of service altogether or declining to adopt a pre-
 sumption at all. The Secretary could reasonably choose a
 familiar short period to avoid what he reasonably found
 would be too demanding an evidentiary standard (no pre-
 sumption) or too lenient a standard (no minimum service
 period) for applying the statutory requirement of service
 connection to veterans with ALS. We conclude that the
 Secretary “reasonably considered the relevant issues and
 reasonably explained the decision” and made a choice
 within the “zone of reasonableness.” Prometheus Radio
 Project, 141 S. Ct. at 1158; see also McKinney, 796 F.3d at
 1383–84 (upholding a regulation where the agency “exam-
 ine[d] the relevant data and articulate[d] a satisfactory ex-
 planation for its action” (internal quotation marks
Case: 20-2168    Document: 27      Page: 17    Filed: 06/09/2021

 SNYDER   v. MCDONOUGH                                     17

 omitted)). We therefore hold that the 90-day-service re-
 quirement of § 3.318(b)(3) is not arbitrary and capricious.
                             III
    For the foregoing reasons, the decision of the Veterans
 Court is affirmed.
     The parties shall bear their own costs.
                         AFFIRMED