Trusted • Evidence-Based • Physician-Led

Providing credible, independent medical opinions that honor service and uphold professional standards.

About Dr. John H. Hart, Jr., M.D.

Dr. John Hart is a board-certified internal medicine physician with over 25 years of clinical experience caring for patients in hospitals and clinics across California. He is certified by the American Board of Internal Medicine and holds an active California medical license. Through his private practice, he provides independent nexus letters for veterans nationwide.

In addition to his civilian practice, Dr. Hart serves as a Lieutenant Colonel and Senior Flight Surgeon in the United States Air Force Reserve. He has deployed multiple times in support of Operation Iraqi Freedom and Operation Enduring Freedom, including service as a Critical Care Air Transport (CCATT) physician. He has held leadership positions such as Chief of Aerospace Medicine at Travis Air Force Base and Director of Hospital Medicine at St. Helena Hospital in California.

Dr. Hart combines his unique experience as both a military physician and a civilian hospitalist to provide veterans with clear, evidence-based nexus letters. His background ensures each opinion is thorough, well-reasoned, and grounded in decades of medical expertise.

Credentials at a Glance:

M.D., Board-Certified in Internal Medicine (ABIM)

Licensed Physician (California) — providing nexus opinions to veterans nationwide

Lieutenant Colonel, USAF Reserve – Senior Flight Surgeon

Over 25 years of medical practice, including hospital medicine, aerospace medicine, and critical care transport

Former Director of Hospital Medicine

Disclaimer:

Dr. Hart provides independent medical opinions in the form of nexus letters for veterans. These services are offered solely through his private practice and are not affiliated with, endorsed by, or representative of the U.S. Air Force, Department of Defense, Department of Veterans Affairs, or any other government agency. All opinions are based on his independent professional medical judgment.

Services

Professional, physician-prepared documentation clarifying medical causation for:

VA Disability Claims (Nexus Letters) – linking current conditions to military service
Dependency & Indemnity Compensation (DIC) Letters – connecting a veteran’s cause of death to service-related conditions

No DBQs or in-person exams. No diagnosis or treatment Secure communication via SimplePractice (HIPAA-compliant)

Typical fees range from $1,500-$3,500 depending on complexity. Rush service (72 hours) available at additional cost.

All opinions are personally authored by Dr. Hart to ensure clarity and professional integrity.

Our Process

Standard turnaround: 10-14 business days Rush: 72 hours

Initial Intake Review

Confirm scope, records, and objectives.

Acceptance & Payment

Secure SimplePractice link provided

Record Review & Analysis

Comprehensive evidence-based assessment

Final Report

Defensible medical opinion suitable for VA and legal use

Reviews

Hart Causation and Claims LLC is an organization I can wholeheartedly support. Dr. John Hart isn’t just an amazing professional—he’s an absolute class act and a superb Senior Flight Surgeon. Having served together in the Air Force over 20 years ago, I can say he still flies high, both in his role and in his humor. His service to the community is as sharp as his wit. If you need top-notch support with a side of laughter, Dr. Hart is your guy!

Peter K. Tiernan, MD, MPH (Retired)

Senior Flight Surgeon

I’m incredibly grateful for the exceptional support I received during one of the toughest times in my life. As a medic lost in the maze of submitting my PTSD application to the VA, I was feeling completely overwhelmed. That’s when Hart Causation and Claims LLC swung in like a superhero team. Dr. John Hart’s kindness and expertise were truly life-changing. He not only expertly guided me through securing my DD 214 form, buddy statement, and personal statement but also reassured me at every step along the way. Dr. Hart isn’t just a clinician—he’s a genuinely trusted friend. His warm, personable nature made the entire process a lot less daunting. I even joked that if he could cook and toss in a hot investment tip, he’d be absolutely perfect!

Linda Dunegan, Lt Colonel, PhD

Medical Service Corps Officer, Retired

Contact

If you are a veteran, surviving spouse, or attorney seeking an independent medical opinion

Get in touch

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Notice:

Submitting information does not create a patient-physician relationship. All communications are confidential and used solely for consulting purposes.

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