## Facts

- A U.S. Army veteran served in Iraq and reported exposure to sand, dust, and smoke from burning garbage.
- After service, he developed chronic respiratory symptoms and received a diagnosis of asthma.
- VA testing reflected both obstructive and restrictive pulmonary findings.
- The veteran sought presumptive service connection for a Gulf War “qualifying chronic disability,” alleging a medically unexplained chronic multisymptom illness (MUCMI) under 38 U.S.C. § 1117 and 38 C.F.R. § 3.317.
- A VA examiner attributed the veteran’s symptoms and test results to asthma and opined he did not have separate obstructive and restrictive diseases.
- The Board of Veterans’ Appeals denied the MUCMI theory, reasoning that asthma could not qualify because its etiology was at least partially understood.

## Issues

1. Under 38 C.F.R. § 3.317(a)(2)(ii), must a diagnosed illness have both an inconclusive etiology and an inconclusive pathophysiology to qualify as a MUCMI, or is either one sufficient?
2. Whether the Board erred by effectively treating asthma as categorically excluded from MUCMI status based on a finding that asthma’s etiology is partially understood.
3. Whether the Board misapplied § 3.317 by failing to assess, for this veteran, whether the illness lacked conclusive etiology or pathophysiology.

## Decision

- The court held that a MUCMI under the first sentence of 38 C.F.R. § 3.317(a)(2)(ii) is established when a diagnosed illness has either an inconclusive etiology or an inconclusive pathophysiology.
- The court rejected the Board’s interpretation that both etiology and pathophysiology must be inconclusive.
- The court set aside the Board’s denial of presumptive service connection under the MUCMI theory and remanded for readjudication under the correct legal standard.

## Legal Principles

- The phrase “without conclusive pathophysiology or etiology” in 38 C.F.R. § 3.317(a)(2)(ii) is disjunctive; VA may not treat “or” as “and.”
- MUCMI status requires a case-specific assessment of whether the veteran’s diagnosed illness lacks conclusive etiology or lacks conclusive pathophysiology; generalized statements that a condition is “partially understood” do not justify categorical denial.
- VA may not categorically exclude a diagnosis (including asthma) from MUCMI consideration solely because some aspects of causation or mechanism are understood.
- When the Board applies an incorrect legal interpretation of a regulation governing presumptive service connection, the proper remedy is vacatur (or setting aside the relevant portion) and remand for application of the correct standard.

## Conclusion

The court clarified that, for Gulf War MUCMI presumptions, a diagnosed illness qualifies if either its etiology or its pathophysiology is not conclusive, and it required VA to reconsider the veteran’s asthma-related disability without imposing a both-elements requirement or categorical exclusions.


Stewart v. Wilkie, 30 Vet. App. 383 (2018)