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.

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 (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, 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.