Jonathan L. Diesenhaus

Jonathan L. Diesenhaus

Partner, Washington, D.C.


Phone +1 202 637 5416

Fax +1 202 637 5910

Practice groupLitigation

Jonathan Diesenhaus advises and advocates for companies and professionals in the life sciences, healthcare, and other regulated industries in civil, criminal, and administrative enforcement matters. Jonathan helps clients respond quickly and efficiently to government investigations, evaluating allegations, reviewing evidence, assessing risk, and identifying strategies to achieve the most appropriate results.

As a leading False Claims Act litigator, he defends qui tam cases brought by whistleblowers and the government in federal courts across the United States. Amid threats of prosecution and fines for retaining overpayments, even when there was no fraud, Jonathan guides his clients through internal investigations, repayment, and when necessary, voluntary disclosures to agencies and law enforcement. His clients include pharmaceutical and medical device companies, hospitals, physician groups, research universities, and academic medical centers.

Jonathan has been prosecuting and defending healthcare and government program fraud cases for over 25 years. From 1998 to 2005, he handled civil healthcare fraud, False Claims Act, and qui tam cases as a senior trial counsel in the Civil Division of the U.S. Department of Justice. He represented the government in matters that established the False Claims Act as a vehicle to pursue violations of the Anti-Kickback Statute, the Stark Law, and of the Food, Drug, and Cosmetic Act. Jonathan has received a number of awards for his work from the U.S. Department of Justice, the FDA, and the Office of Inspector General in the U.S. Department of Health and Human Services.

Jonathan also works with industry and academic trade associations to educate policymakers on the complications of prosecuting healthcare fraud under both state and federal qui tam statutes, on the detrimental impact of the qui tam and federal False Claims Act investigations, and the effect that litigation has on businesses and individuals.

Awards and recognitions


Litigation: White Collar and Government Investigations (District of Columbia)
Chambers USA


Healthcare: Service Providers, Leading Lawyer
Legal 500 US

2014, 2016-2017

Dispute Resolution: Corporate Investigations and White-Collar Criminal Defense
Legal 500 US


Health Care Law
The Best Lawyers in America


Health Care
Washington, D.C. Super Lawyers


Outstanding Fraud and Compliance Lawyer
Nightingale's Health Care News


Martindale-Hubbell 2014 "Preeminent" (5 out of 5) Rating - Litigation, Arbitration and Employment; Health


Inspector General's Integrity Award


Director's Award
Executive Office of the U.S. Attorneys


Civil Division Special Commendations
U.S. Department of Justice


Food and Drug Administration Commissioner's Special Citation

Education and admissions


J.D., University of California, Berkeley Boalt Hall School of Law, 1988

B.A., cum laude, University of Colorado, 1985


Barrister, Edward Bennett Williams Inn of Court

Member, Criminal Justice Section, White Collar Crime Committee, ABA 

Program Chair and Planning Committee Member, ABA National Institute, Health Care Fraud

Section Leadership, Health Law Section, ABA

Bar admissions and qualifications

District of Columbia


Court admissions

U.S. Court of Appeals, District of Columbia Circuit

U.S. District Court, District of Colorado

U.S. District Court, District of Columbia

U.S. Supreme Court

Representative experience

Secured Deferred Prosecution Agreement and civil settlement for represented global biotech company accused of adulterating a surgical adhesion barrier.

Won summary judgment for university in qui tam accusing its anesthesiologists of billing for services they didn't provide.

Resolved criminal and civil Anti-Kickback Statute charges against small pharma company by Deferred Prosecution Agreement and civil settlement.

Defended global generic drug manufacturer in first of its kind civil money penalties settlement with OIG-HHS for misreporting Average Sales Price data.

Favorable settlement after litigation for a New Jersey cardiologist of Stark Law and False Claims Act violations for referring patients to UMDNJ.

Investigated and settled grant fraud allegations for a major academic medical center in New York City.

Handling voluntary disclosures of excluded employee and billing problems for various corporate healthcare providers.

Represented manufacturer of surgical sterilization equipment in FDA civil money penalties action for failure to report manufacturing quality problems.

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