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. Greenberg.

______________________

Decided: June 9, 2021

______________________

JENNIFER ANN ZAJAC, Paralyzed Veterans of America, 

Washington, DC, argued for claimant-appellant. Also represented by LINDA E. BLAUHUT. 

 KYLE SHANE BECKRICH, Commercial Litigation Branch, 

Civil Division, United States Department of Justice, Washington, DC, argued for respondent-appellee. Also represented by JEFFREY B. CLARK, ELIZABETH MARIE HOSFORD,

ROBERT EDWARD KIRSCHMAN, JR.; BRIAN D. GRIFFIN, DEREK 

SCADDEN, Office of General Counsel, United States Department of Veterans Affairs, Washington, DC.

Case: 20-2168 Document: 27 Page: 1 Filed: 06/09/2021
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-connected 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 misconduct or abuse of alcohol or drugs) inapplicable to Mr. 

Snyder. A decision of the U.S. Court of Appeals for Veterans 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 undisputedly 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.

Case: 20-2168 Document: 27 Page: 2 Filed: 06/09/2021
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 certain prescribed preconditions. Section 3.318 provides:

(a) Except as provided in paragraph (b) of this section, the development of amyotrophic lateral sclerosis 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 amyotrophic lateral sclerosis was not incurred 

during or aggravated by active military, 

naval, or air service;

(2) If there is affirmative evidence that amyotrophic lateral sclerosis is due to the veteran’s own willful misconduct; or

(3) If the veteran did not have active, continuous service of 90 days or more.

38 C.F.R. § 3.318 (emphasis added). 

This presumption is entirely a regulatory creation. Although Congress has enacted several provisions that 

Case: 20-2168 Document: 27 Page: 3 Filed: 06/09/2021
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 applicable to ALS. The Secretary promulgated § 3.318 pursuant 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 . . . 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.” 

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 Amyotrophic Lateral Sclerosis, 73 Fed. Reg. 54,691, 54,692 (Sept. 

23, 2008) (Interim Final Rule) (reciting § 501 authority applied to service-connection requirement of § 1110). 

The Secretary’s proposal and adoption of the regulation 

followed receipt of a VA-commissioned report by the National 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 association 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 

Case: 20-2168 Document: 27 Page: 4 Filed: 06/09/2021
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 “quintiles”—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 assigning 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 service, 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 affected rates of ALS, the Weisskopf study found that the relative 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 reported 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.

Case: 20-2168 Document: 27 Page: 5 Filed: 06/09/2021
6 SNYDER v. MCDONOUGH

The 2006 IOM Report observes that, while other studies 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 Report 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 inherent 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 interim final rule—effective immediately but subject to notice 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 progressive and degenerative nature of the disease, as well as “continuing uncertainty regarding specific precipitating factors 

or events that lead to development of [ALS],” the Secretary 

determined that there would be “great difficulty” for veterans 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 establish service connection. See id. First, service connection 

Case: 20-2168 Document: 27 Page: 6 Filed: 06/09/2021
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 “presumption” label. Id. (emphasis added); see also 38 C.F.R. 

§ 3.318(b)(1). Next, service connection would not be presumed 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). Finally, 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 increased risk of developing ALS compared to civilians regardless of years of service, a minimumservice requirement of 90 days would not be inconsistent 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 activities 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 presumptions 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, “Congress considered 90 days to be the minimum period necessary to support an association between such service and 

subsequent development of disease” and “for any shorter 

Case: 20-2168 Document: 27 Page: 7 Filed: 06/09/2021
8 SNYDER v. MCDONOUGH

period, it is more likely than not that ALS was not associated 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 Amyotrophic 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 active 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” regulations that are (1) arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law; (2) 

contrary to constitutional right, power, privilege, or immunity; (3) in excess of statutory jurisdiction, authority, or 

limitations, or in violation of a statutory right; or (4) without 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 exceeding the Secretary’s statutory authority and, second, as arbitrary and capricious. Snyder Opening Br. at 16–29, 29–

39. We must reject these challenges.

Case: 20-2168 Document: 27 Page: 8 Filed: 06/09/2021
SNYDER v. MCDONOUGH 9

A

In promulgating 38 C.F.R. § 3.318, the Secretary invoked 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 Department 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 addresses 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 regulations—like the one at issue here—establishing a serviceconnection 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-connection 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 “associated with exposure to contaminants in the water supply at 

Case: 20-2168 Document: 27 Page: 9 Filed: 06/09/2021
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 “evidence,” 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 benefit the presumption runs, the luxury of not having to produce specific evidence to establish the point at issue. When 

the predicate evidence is established that triggers the presumption, the further evidentiary gap is filled by the presumption.” 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 connection. A veteran with ALS need not “produce specific evidence,” 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 Evidentiary rules like this one are within the Secretary’s rulemaking 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 together with his argument that the presumption must be 

modified to eliminate the 90-day-service precondition.

Case: 20-2168 Document: 27 Page: 10 Filed: 06/09/2021
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 meritless. Section 3.318 does not modify the definition of “veteran,” 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 circumstances. Various regulations make evidentiary distinctions 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 authority. See Snyder Opening Br. at 22–24. But that provision, 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 requirement of being a veteran for general-benefits eligibility, 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 connection 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 

Case: 20-2168 Document: 27 Page: 11 Filed: 06/09/2021
12 SNYDER v. MCDONOUGH

procedural propriety of the promulgation of § 3.318. But 

he does argue that the rule, with its 90-day-service requirement, is arbitrary and capricious. Snyder Opening Br. at 

29–39. We turn to that challenge.

B

Arguing that the 90-day-service requirement is “arbitrary and capricious,” Mr. Snyder contends that (1) the Secretary 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 required for our assessment of this challenge, we must reject 

Mr. Snyder’s argument.

Under 38 U.S.C. § 7292(d)(1), whose pertinent language 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 practice of treating the first two terms in the list as forming a 

single “arbitrary-and-capricious standard.” FCC v. Prometheus 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 Veterans Affairs, 343 F.3d 1347, 1353 (Fed. Cir. 2003). Our 

Case: 20-2168 Document: 27 Page: 12 Filed: 06/09/2021
SNYDER v. MCDONOUGH 13

review of a regulation for compliance with the arbitraryand-capricious standard is “deferential.” Prometheus Radio 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 announcing 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 statutorily required element that a veteran’s ALS is connected 

to “military service,” id. at 54,691, i.e., to “activities in military 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 particularly 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 

Case: 20-2168 Document: 27 Page: 13 Filed: 06/09/2021
14 SNYDER v. MCDONOUGH

“a presumption of service connection” for veterans with 

ALS, id. at 54,691–92. The Secretary simultaneously concluded, however, that the justified presumption was conditional 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 connection likely. See id. (deeming it appropriate to adopt “a 

reasonable period to ensure that an individual has had sufficient contact with activities in military service to encounter any hazards that may contribute to development of 

ALS”). That logic is reasoned and reasonable.

Second, focusing on the record regarding ALS, the Secretary 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 evidence 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 reasonable 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 

Case: 20-2168 Document: 27 Page: 14 Filed: 06/09/2021
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 purpose 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 substances with known risks, either directly or through presence 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 conditions.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.” Hansen-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 evidence in the rulemaking record but ignored by the Secretary. 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)), exposure to Agent Orange in Vietnam (id. § 1116), and service in the Persian Gulf War (id. § 1118).

Case: 20-2168 Document: 27 Page: 15 Filed: 06/09/2021
16 SNYDER v. MCDONOUGH

noted that the ALS Association endorsed the 90-day-service requirement, and Mr. Snyder has not identified any 

contrary comments that went unmentioned by the Secretary. Final Rule, 74 Fed. Reg. at 57,073. Supportive comments “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 evidence 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 Television Stations, Inc., 556 U.S. 502, 519 (2009))). Indeed, 

the Secretary expressly “welcome[d] comments on any relevant peer-reviewed literature concerning ALS that ha[d] 

been published since the November 2006 IOM report.” Interim Final Rule, 73 Fed. Reg. at 54,692. And the Secretary was under “no general obligation . . . to conduct or 

commission [his] own empirical or statistical studies.” Prometheus Radio Project, 141 S. Ct. at 1160.

In these circumstances, neither the evidence nor logic 

required the Secretary to limit his options to either ignoring length of service altogether or declining to adopt a presumption 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 presumption) 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 “examine[d] the relevant data and articulate[d] a satisfactory explanation for its action” (internal quotation marks 

Case: 20-2168 Document: 27 Page: 16 Filed: 06/09/2021
SNYDER v. MCDONOUGH 17

omitted)). We therefore hold that the 90-day-service requirement 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

Case: 20-2168 Document: 27 Page: 17 Filed: 06/09/2021