An accomplished first-chair trial lawyer, Enu Mainigi has represented a number of leading companies and individuals in complex civil and criminal litigation in state and federal courts throughout the country. Enu’s practice focuses on the financial services and health care industries.  She has extensive experience defending financial institutions, health care companies, and executives in all stages of criminal and civil investigation and litigation. Enu serves as Chair of the firm’s False Claims Act and Qui Tam practice, and has in-depth experience representing clients in these industries and others in FCA-related litigation and investigations. She also serves as the Co-Chair of the firm’s Health Care practice.

Enu was named among The National Law Journal’s 75 “Outstanding Women Lawyers” in 2015.  She has also been recognized by The Legal 500 as a leading lawyer in financial services litigation, and has been named a “Litigation Star” in the area of white collar criminal defense, and among the “Top 250 Women in Litigation” by Benchmark Litigation on multiple occasions. Chambers USA includes her as a recommended lawyer for healthcare in their 2015 - 2018 editions, noting that she “wins impressive praise from clients,” who describe her as, “fantastic, really strategic” and "business-savvy.”  One client noted, “She's hands-down the best litigator I've ever met. She has phenomenal strategic vision and great jury presence."

Enu has significant experience representing financial services and banking clients, and serves as Williams & Connolly’s relationship partner for several financial services industry leaders. She has defended financial institutions in government investigations related to the 2008 financial crisis and the subsequent meltdown of the mortgage industry. She regularly represents corporations and individuals under investigation by the government under criminal or civil statutes such as the False Claims Act and FIRREA. 

In addition, Enu has a highly regarded health care practice. She regularly defends health care companies, pharmacy benefit managers, retail pharmacies, hospitals, nursing homes and pharmaceutical companies in high-stakes litigation and government investigations. Her experience representing individuals and corporations in the health care industry includes internal investigations, grand jury probes and other criminal investigations, agency investigations and civil False Claims Act litigation, covering a wide range of issues and statutes, including anti-kickback statutes, the Food Drug and Cosmetic Act, federal and state False Claims Acts, Medicare and Medicaid fraud, and other state and federal statutes.

Enu currently serves as a member of Williams & Connolly’s Executive Committee and is a former member of the Firm’s Hiring Committee. In the winter of 2010-2011, she spent several months as Chair of the Transition of Governor Richard L. Scott of Florida, a long-time client of the Firm.

Prior to joining Williams & Connolly in 1997, Enu served as Director of Policy and Research for Senator Robert Dole’s 1996 Presidential campaign.

Representative Experience

Though all cases vary and none is predictive, Enu’s experience as trial counsel includes:

  • Defending Bank of America in case brought by the Department of Justice for alleged breaches of contractual warranties in connection with the sale of certain mortgages in the wake of the mortgage crisis. The case was won on appeal, reversing a $1.3 billion penalty against Bank of America.
  • Representing CVS Caremark in one of the first qui tam cases to address Medicare Part D service issues, resulting in summary judgment for CVS Health on all of the alleged claims.
  • Winning summary judgment on behalf of Omnicare, Inc., in qui tam litigation concerning procedures for accounts receivable collections for prescription drug services, and now representing Omnicare in an appeal filed by opposing counsel.
  • Ongoing representation of one of the leading financial services companies in the U.S. in connection with an ongoing government investigation into its mortgage lending practices by the U.S. Department of Justice and the Federal Housing Finance Agency Office of Inspector General.
  • Securing a government declination to intervene against Cardinal Health and Edgepark Medical Supplies in the wake of alleged violations of federal healthcare fraud and abuse laws in qui tam litigation that, while dropped against Cardinal and Edgepark, was pursued against other defendants.
  • Successfully defending Express Scripts and Medco Health Solutions in an appeal to the Third Circuit in a case alleging violations of the False Claims Act in connection with the alleged inflation of average wholesale prices for brand-name drugs. The district court granted the clients’ motion to dismiss, and, on appeal, the Third Circuit upheld the dismissal.
  • Defended Fortune 50 company in a comprehensive FCA investigation of and litigation over its business practices by the federal government and 20 states.
  • Defended Fortune 100 corporation in an investigation of its accounting systems and practices.
  • Represented pharmaceutical manufacturers in multiple off-label promotion investigations and litigation.
  • Represented Big 4 accounting firm in a government investigation related to travel expenses.
  • Defended the head of sales of a pharmaceutical manufacturer in an investigation involving “off–labeling” and other issues.
  • Defended former CEO of a healthcare company against a 132-count criminal indictment.
  • Defending a hospital system in a criminal and civil investigations and litigation involving reimbursement and kickback issues.
  • Defended airline in a criminal environmental investigation.
  • Defended insurance carrier in FCA litigation involving Medicare reimbursement issues.

Commercial/Civil Litigation Experience

  • Defended Fortune 50 corporation in ERISA class actions.
  • Defended health care company in AAA arbitration related to data sale issues.
  • Represented pharmaceutical manufacturer in multi-jurisdictional products liability cases.
  • Defended Big 4 accounting firm in derivative litigation emanating from a client’s corporate fraud scandal.
  • Defended Fortune 50 corporation in a six-week trial related to breach of contract and breach of fiduciary duty issues.
  • Defended Fortune 50 corporation in an eight-week trial related to fraud and breach of contract issues.



“Outstanding Women Lawyers,” The National Law Journal, 2015

“Health MVP,” Law360, 2017

“Top 250 Women in Litigation,” Benchmark Litigation, 2015-2018

“National Litigation Star,” Benchmark Litigation, 2017-2019

“Local Litigation Star,” Benchmark Litigation, 2015-2019

“Healthcare (D.C.),” Chambers USA, 2015-2018

“Life Science Star,” LMG Life Sciences, 2018

“Female Powerbrokers Q&A: Williams & Connolly's Enu Mainigi,” Law360, 2014


Government Service

Law Clerk, Judge Franklin S. Van Antwerpen, United States District Court for the Eastern District of Pennsylvania, 1994-1995

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