The nexus letter — a medical opinion establishing the connection between a claimant's diagnosed condition and their overseas service — is the single most important piece of evidence in the majority of DBA claims. Understanding what makes a nexus letter strong or weak is essential for any attorney handling these cases.
What a Nexus Letter Must Establish
A nexus letter must do three things: confirm the diagnosis, identify the relevant exposure or injury mechanism, and state the clinician's opinion — to the applicable legal standard — that the condition is related to the claimant's service. The legal standard is not certainty; it is that the condition is "as likely as not" caused or aggravated by the relevant exposure or incident.
Common Weaknesses
Many nexus letters fail not because the underlying opinion is wrong, but because they are poorly drafted. Generic opinions that do not reference the specific facts of the case, opinions from clinicians who lack relevant specialty expertise, and letters that use hedging language inconsistent with the legal standard are all vulnerable to challenge. Carriers will scrutinise nexus letters carefully and exploit any weakness.
Selecting the Right Clinician
Specialty expertise matters. A pulmonologist is more credible than a general practitioner for a respiratory condition. A board-certified occupational medicine physician carries particular weight in toxic exposure cases. For psychological conditions, a psychiatrist or clinical psychologist with experience in combat and deployment-related trauma is essential.
The Independent Medical Examination
Carriers frequently obtain their own Independent Medical Examination (IME) to counter claimant nexus evidence. Understanding how to challenge a carrier's IME — through cross-examination, rebuttal opinions, and exposure of methodological weaknesses — is as important as building the primary nexus evidence. An IME that relies on an inadequate records review or fails to account for known exposure data is vulnerable to attack.