Jonathan Diesenhaus advises and advocates for companies and professionals in the life sciences, health care, and other regulated industries surrounding civil, criminal, as well as administrative enforcement matters.
Diesenhaus helps clients respond quickly and efficiently to government investigations, evaluating allegations, reviewing evidence, assessing risk, and identifying strategies to achieve the most appropriate results.
Lawdragon Honors
| Honor | Year | Practice |
|---|---|---|
| The 2026 Lawdragon 500 Leading Global Investigations Lawyers | 2026 | Investigations, False Claims Act, Enforcement, Life Sciences |
As a leading False Claims Act (FCA) 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 over payments, even when there was no fraud, Diesenhaus 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.
Diesenhaus has been prosecuting and defending health care and government program fraud cases for over 25 years. From 1998 to 2005, he handled civil health care fraud, FCA, and qui tam cases as a senior trial counsel in the Civil Division of the U.S. Department of Justice (DOJ). He represented the government in matters that established the FCA as a vehicle to pursue violations of the Anti-Kickback Statute, the Stark Law, and the Food, Drug, and Cosmetic Act. Diesenhaus has received a number of awards for his work from the DOJ, the U.S. Food and Drug Administration, and the Office of Inspector General in the U.S. Department of Health and Human Services.
Diesenhaus also works with industry and academic trade associations to educate policymakers on the complications of prosecuting health care fraud under both state and federal qui tam statutes, on the detrimental impact of qui tam and federal FCA investigations, and the effect that litigation has on businesses and individuals.