Mark P. Guerrera

MARK GUERRERA represents clients facing high-stakes commercial litigation and government investigations. He has tried cases in federal court and before regulatory agencies and has spent a significant part of his practice representing clients in cross-border litigation in Italy, Liechtenstein, Switzerland, and the Cayman Islands, among others. Mark’s clients include some of the largest companies in the financial services, pharmaceutical, energy, telecommunications, government contracting, and real estate industries. Many of his cases have involved allegations of fraud and other business torts, breach of fiduciary duty, deepening insolvency, market manipulation, unfair business practices, securities fraud, breach of contract, and violations of state and federal statutes, including the False Claims Act and RICO. He also has litigated class action securities matters, government contracts disputes, bid protests, and intellectual property disputes. A number of the cases Mark has litigated have involved multi-billion dollar damage claims.

Mark has also conducted internal investigations on behalf of companies in the U.S. and abroad. He has defended companies in connection with government investigations regarding allegations of fraud, accounting irregularities, employee misconduct, and violations of the False Claims Act, anti-bribery, anti-money laundering, federal securities, and banking laws.

Mark served for ten years as a co-leader of Sidley's global Commercial Litigation and Disputes practice.

Prior to joining Sidley, Mark clerked at the Armed Services Board of Contract Appeals.

Recent representations include:

• United States ex rel. Siegel v. Novo Nordisk, Inc. — full defense verdict following a three-week jury trial in a False Claims Act suit alleging off-label promotion and violations of the Anti-Kickback Statute in connection with certain patient support programs and physician relationships. This marks the first-ever pharmaceutical defense verdict in an FCA jury trial.
• Major international bank in cross-border litigation in Italy, Switzerland, and Liechtenstein involving claims of fraud, deepening insolvency, market manipulation, among others.
• Energy developer in litigation in federal court relating to the financing, construction, and leasing of a major power plant.
• Financial services providers in arbitration and disputes regarding co-branded credit card agreements.
• Private equity firm in the enforcement of an award from the International Centre for Settlement of Investment Disputes.
• Telecommunications company in federal court actions alleging violations of the Telecommunications Act.
• Commercial real estate company in litigation regarding property rights and alleging claims for breach of contract. 
• Big Four accounting firm partner and employee in PCAOB investigation.
• Pharmaceutical manufacturers in connection with affirmative claims for violations of the Lanham Act.
• Pharmaceutical distributor in federal court litigation, alleging claims of fraud and breach of contract.
• Pharmaceutical manufacturer in connection with disputes regarding the Prescription Drug User Fee Act.
• Foreign executive in connection with a multinational bribery investigation and related proceedings in the United States, Italy, and Africa.
• GSA Schedule contractor in connection with a qui tam lawsuit and related DOJ investigation under the False Claims Act alleging violations of the price reduction clause. 
• Interstate natural gas pipeline in an enforcement proceeding before the Federal Energy Regulatory Commission.
• Pharmaceutical manufacturers in connection with internal reviews of FDA regulatory issues.
• Financial institution in a series of cases arising out of the collapse of Italian dairy giant, Parmalat S.p.A. Obtained multiple victories on motions to dismiss, summary judgment, and at trial — all of which were affirmed.
• Financial service provider in connection with anti-money laundering compliance matters and related government investigations.
• Defense contractor in a four week trial against the United States Air Force.
• Satellite manufacturer in a six week international arbitration.
• Major financial institution in qui tam “whistleblower” lawsuits under the False Claims Act regarding securitization and foreclosure practices. See, e.g., U.S. ex rel. Adams v. Wells Fargo Bank, N.A., 2013 U.S. Dist. LEXIS 175322 (D. Nev. Dec. 11, 2013). 
• Nursing home owner in a DOJ investigation under the False Claims Act.

• Washington Lawyers’ Committee for Civil Rights and Urban Affairs, Board Member 
• Georgetown University Board of Governors, Board Member
• The Hoya Hoop Club, President