Skip to main content
580 verified sources — free, no sign-up

The research & law behind your claim

Every citation behind your claim is real and checkable — each links to its PubMed or DOI record and the controlling law. The VA weighs evidence it can verify, so we show you every source. Browse the peer-reviewed studies and the controlling law behind VA claims, by condition and legal theory.

Medical evidence by condition

580 verified, peer-reviewed studies across 32 condition groups — each links out to its real PubMed or DOI record. These are the sources our nexus drafts draw from; nothing here is invented.

Acquired Flatfoot

38 CFR DC 5276

Foot structure and intensive training/overuse driving pes planus and related lower-extremity overuse injury in recruits and service members.

Cervical Degenerative Disc Disease

Helmet/NVG head-borne loads, aircrew exposures, load carriage, and trauma producing chronic neck pain and cervical spine disease in service members.

Chronic Ankle Instability

38 CFR DC 5270, 5271, 5272, 5274

High incidence of ankle sprains and chronic lateral ankle instability from military training, load carriage, and uneven terrain.

Chronic Multisymptom Illness

38 CFR DC 6354

Gulf War deployment exposures and chronic multisymptom illness associated with chronic fatigue syndrome/ME in veterans.

Chronic Obstructive Pulmonary Disease

38 CFR DC 6510, 6511, 6512, 6513, 6514, 6522…

Open burn-pit smoke and aerosolized desert particulate exposure in the Southwest Asia theater (Iraq, Afghanistan, and the broader theater) as a cause of chronic respiratory disease; and, for the sinonasal conditions, the recognized secondary pathways to chronic rhinosinusitis under 38 C.F.R. § 3.310 (GERD/laryngopharyngeal reflux, septal deviation from in-service nasal trauma, and asthma/type 2 airway inflammation).

Chronic Widespread Pain

38 CFR DC 5025

Gulf War service and PTSD/central-sensitization mechanisms associated with fibromyalgia and chronic widespread pain in veterans.

Contact Dermatitis

38 CFR DC 7806

Occupational skin irritant/allergen exposure and deployment conditions associated with eczema and contact/atopic dermatitis in service members.

Coronary Artery Disease

38 CFR DC 7005

PTSD/combat-stress association with incident ischemic heart disease supporting secondary service connection.

Degenerative Disc Disease

38 CFR DC 5237, 5238, 5239, 5242, 5243, 5244…

Heavy load-bearing/rucksack carriage and low back pain incidence in service members.

Degenerative Joint Disease

38 CFR DC 5055, 5256, 5257, 5258, 5259, 5260…

Elevated incidence of knee osteoarthritis and post-traumatic OA in military service members.

Diabetes Mellitus

38 CFR DC 7913

Herbicide (Agent Orange) exposure association with type 2 diabetes underpinning the presumptive.

Erectile Dysfunction

38 CFR DC 7522

Erectile dysfunction in veterans arises predominantly as a SECONDARY condition — to PTSD and depression and to the serotonergic medication used to treat them, to service-connected diabetes mellitus and hypertension and antihypertensive therapy, to obstructive sleep apnea, to lumbar and spinal cord pathology, and to treatment for service-connected prostate cancer — with a real minority DIRECT lane in deployment genitourinary and pelvic blast trauma.

Femoroacetabular Impingement

38 CFR DC 5250, 5251, 5252, 5253, 5254, 5255

Load-bearing, training overuse, and post-traumatic mechanisms driving femoroacetabular impingement and hip osteoarthritis in service members.

Frequent Nighttime Urination

38 CFR DC 7542

Obstructive sleep apnea as a recognized cause of nocturia/nocturnal polyuria (secondary service connection).

Gastroesophageal Reflux Disease

38 CFR DC 7346

PTSD/combat-stress and deployment exposures associated with gastroesophageal reflux disease in service members and veterans.

Generalized Anxiety Disorder

38 CFR DC 9400

Prevalence and course of anxiety disorders in service members and veterans, supporting direct and secondary service connection.

High Blood Pressure

38 CFR DC 7101

Herbicide exposure and hypertension (National Academies Update 11: sufficient evidence of an association, the basis for the PACT Act presumptive) and open-burn-pit deployment, plus combat exposure and injury severity, occupational job strain, rotating shift work and noise as direct exposures — with the PTSD/combat-stress and obstructive-sleep-apnea pathways supporting secondary service connection.

Indirect Inguinal Hernia

38 CFR DC 7338

Occupational mechanical exposures — heavy lifting, carrying, and prolonged standing/walking characteristic of military duty — and their association with inguinal hernia requiring repair.

Lumbosacral Radiculopathy

Heavy load carriage, rucksack carriage, and spinal trauma producing cervical and lumbar radiculopathy in service members.

Major Depressive Disorder

38 CFR DC 9434, 9440

Deployment and military-service mental-health burden and the course of major depressive disorder in service members and veterans.

Median Nerve Entrapment

38 CFR DC 8515

Repetitive forceful hand/wrist use and vibration exposure (occupational) associated with carpal tunnel syndrome in service members.

Mild Traumatic Brain Injury

38 CFR DC 8045

Blast overpressure, mounted and dismounted IED exposure, combat and training head trauma, and repetitive low-level blast from breaching, artillery and heavy weapons as the DIRECT cause of traumatic brain injury in service members — the deployment-era epidemiology establishing the in-service injury event, the imaging and neuropathology evidence that blast produces an objectively distinct brain injury, and the longitudinal evidence that symptoms and disability persist for years after separation, which is the basis on which residuals-of-TBI claims are most often denied.

Obstructive Sleep Apnea

38 CFR DC 6847

Deployment-associated OSA risk and rising in-service incidence, plus the sleep-restriction and sleep-fragmentation physiology that reduces genioglossus drive and raises upper-airway collapsibility — supporting DIRECT service connection; with the PTSD, nasal-obstruction, post-injury weight-gain, and TBI pathways supporting secondary service connection.

Peripheral Neuropathy

Herbicide (Agent Orange) and other toxic/organophosphate exposures and combat nerve trauma associated with peripheral neuropathy in veterans.

Plantar Fasciopathy

38 CFR DC 5269

Running, marching, prolonged standing, and load carriage driving plantar fasciitis in the military population.

Post-traumatic Headache

38 CFR DC 8100

Deployment-related traumatic brain injury and post-traumatic headache/migraine in service members and veterans.

Post-traumatic Stress Disorder

38 CFR DC 9411

Combat and deployment stressor exposure and the epidemiology of PTSD in service members and veterans, supporting direct service connection.

Postinfectious Irritable Bowel Syndrome

38 CFR DC 7319

Deployment-acquired infectious gastroenteritis (travelers' diarrhea, Campylobacter, Shigella, norovirus, C. difficile) as the documented antecedent of post-infectious irritable bowel syndrome in active-duty and deployed US personnel, together with the operational-stress and Southwest Asia theater literature that places functional gastrointestinal disorders including IBS among the chronic multisymptom presentations of Gulf War service.

Ringing In The Ears

38 CFR DC 6260

Military noise and blast exposure as the direct cause of tinnitus — prospective new-onset incidence in service members against a civilian baseline, plus the cochlear-synaptopathy ("hidden hearing loss") mechanism that explains tinnitus with a NORMAL audiogram, which is the basis on which these claims are most often denied.

Sensorineural Hearing Loss

38 CFR DC 6100

Hazardous military noise exposure (weapons, aircraft, armor, blast) and noise-induced sensorineural hearing loss in service members.

Shoulder Impingement

38 CFR DC 5024, 5201, 5202, 5203

Repetitive overhead load, heavy lifting, and training/combat trauma driving rotator-cuff and shoulder instability injuries in service members.

Unstable Scar

38 CFR DC 7800, 7801, 7802, 7804, 7805

Service-incurred wounds, burns, and surgeries producing painful, unstable, or neuropathic residual scars.

Controlling law by theory

The CFR sections and published cases each theory of service connection actually rests on. This describes the legal standard raters evaluate against — it is never a prediction about any claim.

Regulation (CFR / USC)

  • 38 C.F.R. § 3.303

    Direct service connection — a current disability linked to service. (Continuity of symptomatology under § 3.303(b) is limited by case law to the § 3.309(a) chronic diseases — Walker.)

Case law

  • Shedden v. Principi, 381 F.3d 1163 (Fed. Cir. 2004)

    The three-element test: current disability, in-service event, and a nexus between them.

  • Holton v. Shinseki, 557 F.3d 1363 (Fed. Cir. 2009)

    Federal Circuit restatement of the same three direct-service-connection elements.

  • Caluza v. Brown, 7 Vet. App. 498 (1995)

    The evidentiary framework a rater weighs each element against.

  • Walker v. Shinseki, 708 F.3d 1331 (Fed. Cir. 2013)

    Continuity of symptomatology (§ 3.303(b)) is available ONLY for a chronic disease listed in § 3.309(a); any other condition must use the medical-nexus pathway.

  • Davidson v. Shinseki, 581 F.3d 1313 (Fed. Cir. 2009)

    A categorical 'a medical opinion is always required for nexus' is legal error — competent lay evidence can suffice.

  • Jandreau v. Nicholson, 492 F.3d 1372 (Fed. Cir. 2007); Layno v. Brown, 6 Vet. App. 465 (1994)

    A veteran is competent to report symptoms they personally observe (Layno), and lay evidence can even establish a simple diagnosis in the right case (Jandreau).

  • McLendon v. Nicholson, 20 Vet. App. 79 (2006)

    A LOW threshold — evidence that merely indicates a nexus MAY exist obligates VA to provide a C&P exam.

  • 38 U.S.C. § 5107(b); Gilbert v. Derwinski, 1 Vet. App. 49 (1990)

    When the evidence is in relative equipoise, the tie goes to the veteran — the preponderance must be AGAINST the claim to deny it.

How to read this

This is educational information about the evidentiary standards and medical literature relevant to VA disability claims — not legal or medical advice, and never a prediction about any claim or rating. Every study links to its PubMed or DOI record so you can verify it yourself; every legal authority is cited as it appears in filings. If you want a nexus opinion built to this standard for your own records, it's drafted from your file and routed to a licensed provider to review and sign.

Ready to build your documentation?

Generate and review your claim documents free — grounded in these sources. Decide after you read them.

Generate your documentation — free