Overview

Ann O'Brien is a partner and Co-Leader of the firm's Antitrust and Competition Practice Group. She also leads the firm’s Criminal Antitrust and Cartels Team. Ann is based in the firm's Washington, D.C. office. 

“Ann O'Brien is a leading antitrust practitioner in the areas of criminal and parallel proceedings. Her experience of almost 20 years at the DOJ provides valuable insight and is of great assistance from a strategic standpoint. Ann is always on top of the matter and is proactive in her approach.”
- Antitrust client, Chambers USA 2024

Areas of Practice

Ann's practice focuses on advising clients facing criminal and civil government antitrust investigations or litigation. Ann leverages her two decades of U.S. Department of Justice experience to provide valuable insider insight on antitrust agency priorities, goals, and policies to strategically guide companies and individuals facing international, domestic and multi-agency antitrust and competition exposure. She has substantial experience leading every aspect of domestic and international antitrust and white collar investigations and prosecutions, including litigating federal criminal jury trials. Additionally, Ann provides clients with cutting-edge compliance counseling and training that can help deter or quickly detect antitrust exposure, informed by what is most important to the DOJ, FTC, and the courts. 

Ann has extensive knowledge of antitrust enforcement practices and policy decisions, gained from her time as a federal prosecutor and manager at the U.S. Department of Justice in the Antitrust Division and as a Special Assistant United States Attorney in the District of Maryland. During her nearly 20-year tenure, Ann assumed numerous senior leadership and management positions in the Antitrust Division, notably as the Assistant Chief of two sections and as the Acting Director of Criminal Enforcement. She was involved in virtually every major criminal enforcement and policy decision made by the Antitrust Division for nearly two decades, and reviewed and approved hundreds of case recommendations, leniency recommendations, search warrants, and requests for grand jury or preliminary inquiry authority. Notably, she gained comprehensive knowledge of global antitrust leniency self-reporting programs and antitrust corporate compliance while developing strong relationships with domestic and foreign antitrust enforcers and regulators. Additionally, Ann served as the Antitrust Division representative on the Financial Fraud Enforcement Task Force, as well as a member of the Grant Fraud Working Group and Oil and Gas Price Fraud Working Group. Ann also has extensive experience advising clients on price-gouging issues and representative client's facing state price-gouging investigations.

Ann and the Sheppard Mullin cartels team have extensive experience representing corporate and individual clients in recent, novel civil and criminal antitrust no-poach and criminal monopolization investigations and litigation. Ann is also part of Sheppard Mullin’s AI team, providing clients with guidance and representing clients in FTC and DOJ antitrust and consumer protection investigations and litigation involving the use of AI.

Having established herself as a thought leader in the antitrust community, Ann regularly speaks and writes on a broad-range of antitrust topics, including serving as co-editor of Competition Policy International’s Cartel column and editing the ABA’s Antitrust Cartel Leniency and Sentencing Handbook. She has also trained hundreds of antitrust prosecutors and law enforcement agents, and served as a liaison to other DOJ components and government agencies. Utilizing her in-depth understanding of antitrust policy and prosecution, Ann skillfully guides clients through their unique antitrust and white collar matters. 

Experience

Experience

Criminal Antitrust Investigations

  • Representing global engineering and technology solutions company Cyient in criminal antitrust investigation alleging novel “no-poach” agreements between an aerospace provider and its outsource engineering services providers to restrict the hiring and recruiting of engineers and skilled laborers working on aerospace projects. The U.S. Department of Justice’s third criminal criminal no-poach trial against six aerospace industry executives and managers, including a Cyient executive, for their alleged participation in the conspiracy resulted in an unprecedented judicial acquittal in April 2023. The criminal investigation closed without additional corporate or individual charges.
  • Representing a health system in a non-public criminal antitrust investigation, successfully navigating client through novel unilateral criminal monopolization investigation.
  • Representing a non-profit institute and public university in a non-public criminal antitrust bid-rigging investigation conducted by the Antitrust Division led-Procurement Collusion Strike Force.
  • Represented a corporate subject of one of the first criminal no-poach and wage-fixing prosecutions. 
  • Representing an individual healthcare executive in an Antitrust Division criminal price-fixing and obstruction investigation, resulting in no charges for client. 
  • Representing a Fortune 100 multinational communications and technology company in a non-public criminal antitrust investigation of an alleged hub-and-spoke price-fixing cartel, resulting in no charges for client or its executives. 
  • Representing Fortune 500 energy company through Antitrust Division Leniency Policy marker process in matter presenting complex legal and factual issues. 
  • Representing individual petroleum company executive in non-public criminal antitrust investigation market-allocation, resulting in no charges for client.  
  • Representing an individual digital advertising executive in an Antitrust Division criminal no-poach investigation, resulting in no charges for client. 

FCPA

  • Worked on a parallel DOJ Criminal and Antitrust Division and FCPA and antitrust investigation reaching a first-of-its-kind corporate resolution binding both the Antitrust and Criminal Division and resulting in $579 million in criminal fines and disgorgement – the second-largest FCPA fine paid by a U.S. company at that time. 

Litigation

  • Defending Realty One Group, Inc. against antitrust claims relating to alleged conspiracy to fix buyer broker commissions on residential real estate transactions. 
  • Defending Essex Property Trust (NYSE: ESS) against antitrust claims relating to alleged conspiracy to fix rental rates for multifamily apartment units using industry software and algorithm provided by RealPage. In re RealPage, Inc. Rental Software Antitrust Litigation (No. II), Case No. 23-3071 (M.D. Tenn.)
  • Defending Cyient, Inc. against antitrust claims brought by a putative class of aerospace engineers alleging a “no-poach” conspiracy between employers not to hire from each other. Borozny et al. v. Raytheon Technologies Corporation, Pratt & Whitney Division, et al., Case No 3:21-cv-01657 (D. Conn.).
  • Defending Hartford HealthCare Corporation against monopolization claims brought by competitor Saint Francis Hospital and Medical Center in federal court, and also against related class action brought by a putative class of individuals enrolled in commercial health plans. Saint Francis Hospital and Medical Center, Inc. v. Hartford Healthcare Corporation, Case No. 3:22-cv-00050-AVC (D. Conn.) and John Brown et al. v. Hartford HealthCare Corp., Case No. HHD-CV22-6152239-S (Superior Court of the Judicial District of Hartford).
  • Representing a fitness platform third-party in FTC v. Meta, DOJ Apple investigation and In re Google Play Antitrust Litigation civil antitrust lawsuits. 
  • Representing corporate advertiser third-party subpoena recipient in S. v. Google and State of Colorado et al. v. Google civil antitrust lawsuits. 
  • Representing an advertising platform third-party CID recipient in Texas attorney general antitrust investigation of Google. 

Civil Competition and Consumer Protection Investigations

  • Representing a professional sports team as a third-party in the Ticketmast/LiveNation antitrust decree violation investigation.
  • Representing a beverage retailer in FTC Robinson-Patman Act investigation regarding discriminatory practices or engaged in other unfair methods of competition in violation of Section 5 of the FTC Act.
  • Representing an AI-powered app developer and platform in FTC consumer protection investigation of novel AI as a means or instrumentality to write fake reviews in violation of Section 5 of the FTC Act.
  • Worked on international extraditions involving antitrust defendants and foreign assistance requests pursuant Mutual Legal Assistance Treaties (MLAT) and International Antitrust Enforcement Assistance Act (IAEAA).
  • Providing antitrust compliance advice and training for multiple global companies. 

Honors

Honors

Top Author, JD Supra Readers' Choice Awards, 2024

Global Competition Review’s "Women in Antitrust 2021” list, which recognizes 138 women around the world for their accomplishments in the antitrust field 

Recommended in Litigation: Civil litigation/class actions, The Legal 500 United States, 2021, 2023-2024

U.S. Department of Justice, Antitrust Division 

  • Assistant Attorney General Award, 2006, 2015 
  • Special Achievement Award, 2009 

Counsel of the Inspectors General on Integrity and Efficiency: Award for Excellence, 2013

U.S. General Services Administration OIG: Special Recognition Award, 2012 

  • JD Supra Top Author 2024
  • Legal 500 Recommended Lawyer 2024

Insights

Articles

"Prepare For NLRB Collaboration With Antitrust Agencies," Law360, August 2022

"Not Guilty: Juries Acquit in First Criminal Antitrust No-Poaching and Wage-Fixing Trials," Today's General Counsel, May 2022

"Antitrust Division Wins First Round in No-Poach Case, but There Is Lots More to Watch," American Health Law Association, April 2022

AI Law and Policy Blog Posts

Antitrust Law Blog Posts

Media Mentions

Speaking Engagements

  • "Understanding the Legal Landscape: Antitrust Considerations," 2024 WHLC Women in Healthcare Leadership Summit, October 24, 2024
  • "Law Firm Leadership Panel and Networking Reception," Georgetown Antitrust & Competition Law Association, February 28, 2024

Events

Memberships

Memberships

  • ABA Antitrust Section, International Cartel Task Force, 2024 to 2025
  • CYO Youth Basketball Coach (2018) 
  • Justice Department Child Development Center, Just Us Kids 
    • Vice President (2016 to 2017) 
    • Board Member (2015 to 2016) 
  • Shrine of the Most Blessed Sacrament Parish and School 
    • Giving Tree Holiday Gift Giving Program: Coordinator (2014 to 2016) 
    • School Advisory Board, Strategic Planning Extracurricular Committee: Member (2015 to 2018) 

Digital Media

Client Testimonials

Client Testimonials

“Ann O'Brien was instrumental in bringing up the legal strategy for the case. She has great client relationship skills. She is empathetic and intuitive. She is a very effective collaborator. Ann previously worked at the DOJ. …She is extremely impressive. She knows the ins and outs of the DOJ, both as lead prosecutor and from various management positions she held. She has a wealth of experience and tremendous credibility not just with the DOJ, but also with those outside of the US. She has really translated it into practice with sound advice. She is good at anticipating the DOJ's moves. She has very good relationships with the DOJ. She is viewed as a fighter; she is able to vigorously represent clients. – Antitrust client, Chambers USA, 2024

“Ann O’Brien is incredibly smart, considerate and supportive, keeping me informed and answering my questions. She understood that being from another country, I needed more explanations than people familiar with the US justice system.” – Antitrust client, Legal 500 US, 2024

“Ann O’Brien did a fantastic job.” – Antitrust client, Legal 500 US, 2024

“Sheppard Mullin’s cartel defense practice has defended multinationals in some of the largest U.S. civil antitrust cartel proceedings in the nation’s litigation history. With the addition earlier this year of former DOJ Antitrust Division’s Ann O’Brien, D.C. attorneys have a laser focus on the criminal component of U.S. antitrust law.” – Antitrust client, Legal 500 US, 2024

“[Sheppard Mullin’s] ability to handle complex and sophisticated [antitrust] matters is very strong…The addition of Ann O'Brien to the Sheppard Mullin team has given Sheppard Mullin the ability to handle complex [matters]. Their service levels and responsiveness are very strong. Ann O'Brien is always on top of the matter and is proactive in her approach. Their ability to deliver to budget and provide overall value for money is very strong." – Antitrust client, Chambers USA, 2024

“Ann O'Brien's client service and general level of service, level of sophistication and commercial vision are all very strong. I loved working with Ann. I trusted her and felt she had my best interests at heart at all times. She was sensitive to my concerns and personal situation, and was caring and professional throughout. I am lucky to have had her as my lawyer.” – Antitrust client, Chambers USA, 2024

“Ann O'Brien is an expert in criminal antitrust matters. That is her real specialty. She spent many years in the DOJ and she can really flex the hardest in investigations work. Aside from the DOJ expert investigations process, she is not afraid to fight. I think because of that and her confidence in her knowledge of DOJ investigations, practice and laws, she was able to really fight and defend.” – Antitrust client, Chambers USA, 2024

“Ann O'Brien's client service and general level of service, level of sophistication and commercial vision are all very strong. Ann is a leading antitrust practitioner in the areas of criminal and parallel proceedings. Her experience of almost 20 years at the DOJ provides valuable insight and is of great assistance from a strategic standpoint. The addition of Ann O'Brien to the Sheppard Mullin team has given Sheppard Mullin the ability to handle complex [specific matters]. This adds to the prior expertise in [specific area] matters. Ann O'Brien is always on top of the matter and is proactive in her approach.” – Antitrust client, Chambers USA, 2024

*Nothing on this site predicts or guarantees future results.

Education

J.D., Northeastern University School of Law, 1999 

B.A., Government and International Studies, University of Notre Dame, 1996 

Admissions

  • U.S. Supreme Court 
  • U.S. Court of Appeals, Fourth Circuit 
  • U.S. District Court, District of Connecticut 
  • U.S. District Court, District of Columbia 
  • U.S. District Court, District of Maryland 
  • Maryland 
  • District of Columbia 
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