I have been on both sides of this, as a disabled veteran who fought my own claim, and as an accredited agent who has fought thousands more. The single biggest predictor of winning is not the strength of the first application. It is persistence.

The first “no” is not the answer

The appeals system exists precisely because first decisions are so often wrong. A denial is a document that tells you what to fix. Veterans who read it that way, and come back with the missing piece, win at far higher rates than those who file once and walk away.

Fight smart, not just hard

Persistence without strategy is just frustration. Persistence aimed at the exact deficiency the VA cited is how claims get overturned. That is the whole reason to have an accredited advocate in your corner: so the fight is targeted, the deadlines are protected, and you are not carrying it alone.

The regulatory authority behind toxic-exposure claims lives in M21-1, Part IV, Subpart ii, Chapter 2, Section C (Service Connection for Disabilities Resulting from Exposure to Environmental Hazards). This section governs how raters develop and adjudicate toxic-exposure claims, including burn-pit, Agent Orange, contaminated-water, and radiation claims, and cross-references the PACT Act's conceded-exposure framework under 38 U.S.C. §1168 (TERA). When a C&P examiner renders a negative nexus opinion without addressing the documented exposure pathway, that opinion is inadequate under Barr v. Nicholson, and raters are required to return it for a supplemental opinion. Veterans who receive a denial after a cursory exam should cite the specific M21-1 development procedures the rater failed to follow.