Mr. Gruenstein regularly advises clients in connection with criminal and regulatory investigations, including those conducted by the U.S. Department of Justice, the U.S. Securities and Exchange Commission and other federal and state regulatory agencies. He also represents boards of directors and their committees on issues related to corporate governance and regulatory compliance and conducting independent investigations on behalf of boards and board committees. Mr. Gruenstein has represented clients in the financial services, energy, healthcare and pharmaceutical, telecommunications, consumer, transportation, fintech, media and entertainment, technology, and life science industries. He has handled both domestic and cross‑border investigations, including in Latin America, Asia and Europe.

Mr. Gruenstein also routinely represents corporate clients in a broad range of civil litigation matters. Examples of recent cases he handled include:

• Won dismissal of litigation filed in New York federal court against Polar Air by Cargo on Demand (“COD”). The plaintiff alleged violations of the federal Racketeer Influenced and Corrupt Organizations (RICO) statute and common law fraud claiming that former members of Polar senior management conspired to overcharge COD by demanding COD make payments to them as a condition of doing business with Polar;
• Won dismissal of a shareholder derivative suit filed in New York Supreme Court against current and former directors and officers of Novartis and several Novartis subsidiaries alleging that the Defendants breached their fiduciary duties to Novartis by failing to conduct adequate oversight of the Company’s operations;
• Won a trial decision for Occidental Petroleum in a Delaware Court of Chancery action seeking inspection of Occidental’s books and records in connection with the company’s $57 billion acquisition of Anadarko Petroleum Corporation, which clarified the scope of Delaware Section 220 authority in cases where books and records demands are made in furtherance of stockholder proxy disputes; and
• Won dismissal of putative securities class action litigation filed against Occidental Petroleum and certain of its officers and directors in New York state court relating to securities offerings conducted in connection with Occidental’s $57 billion acquisition of Anadarko Petroleum.

Mr. Gruenstein maintains an active pro bono practice. He is a member of the Criminal Justice Act Panel, authorized to represent indigent defendants in cases before the Second Circuit and in the Southern District of New York. Recently, Mr. Gruenstein led a team of Cravath attorneys in submitting an amicus brief on behalf of the Innocence Network in support of death row inmate Melissa Lucio’s application for habeas corpus and motion to stay execution. Just two days before the scheduled execution, on April 25, 2022, the Texas Court of Criminal Appeals issued a per curium opinion staying the execution and remanding the habeas claims to the trial court for a merits review. 

Mr. Gruenstein is a member of the American Law Institute, the Supreme Court Historical Society Board of Trustees, and the International Bar Association, and a fellow of the American Bar Foundation and the International Academy of Financial Crime Litigators.

Mr. Gruenstein routinely writes and appears as a speaker at seminars and conferences with regard to regulatory enforcement, investigations and compliance matters. He co-authored a working paper entitled, “Secret Notes And Anonymous Coins: Examining FinCEN’s 2019 Guidance On Money Transmitters In The Context Of The Tornado Cash Indictment,” which was published by The International Academy of Financial Crime Litigators (September 2023). Mr. Gruenstein also authored the article “The Risks of ‘Too Much’ Entanglement with the Government When Conducting Internal Investigations” for the inaugural issue of the Bulletin of The International Academy of Financial Crime Litigators (June 2023); the chapter, “Director and Officer Liability in the United States” in Handbuch Managerhaftung (2023), a leading German corporate law treatise on director and officer liability; and a chapter on corporate compliance programs in the 2016-2018 editions of Corporate Governance: Law & Practice. Among other speaking engagements, Mr. Gruenstein addressed developments in deferred prosecution agreements in the American Bar Association’s 2023 International Law Section Annual Conference, and compliance topics of interest to Boards of Directors at ECI’s IMPACT 2023 Conference and EY’s Chief Compliance & Ethics Officer Roundtable for the Consumer Products Sector.

Benchmark Litigation has recognized Mr. Gruenstein as a “National Star” in white‑collar criminal defense and investigations, as well as a “Litigation Star” in New York. The Best Lawyers in America has also recognized him for his white‑collar criminal defense work. He has been recognized by The Legal 500 US for his work in white‑collar criminal defense, general commercial disputes, securities litigation and related regulatory enforcement matters and for his experience in the media and entertainment industry. Mr. Gruenstein has been selected by Lawdragon as one of “500 Leading Lawyers in America” and “500 Leading Litigators in America,” and was named a nationwide “Legend.” Chambers USA recognized him as a leading lawyer in White‑Collar Crime & Government Investigations, with a client calling him “the most strategic lawyer I’ve ever worked with” and a peer describing him as having “impeccable judgment” and “total command of the facts of a case” and as being “outstanding with clients.”

Together with his Cravath colleagues, Mr. Gruenstein earned the Firm a top‑tier ranking for Criminal Defense: White‑Collar in the Best Lawyers Best Law Firms survey.

Mr. Gruenstein was born in New York, New York. He received an A.B. summa cum laude in Philosophy and Mathematics from Harvard College in 1996, where he was elected to Phi Beta Kappa, and a J.D. magna cum laude from Harvard Law School in 1999, where he was an editor of the Law Review. After graduating from law school, Mr. Gruenstein served as a law clerk to Hon. Stephen F. Williams of the U.S. Court of Appeals for the D.C. Circuit and to Justice David H. Souter of the U.S. Supreme Court.

Prior to joining Cravath, Mr. Gruenstein served as an Assistant U.S. Attorney in the Criminal Division of the U.S. Attorney’s Office for the Southern District of New York from 2002 to 2008.

Mr. Gruenstein joined Cravath in 2008 and was elected a partner in 2011. He serves as the Litigation Hiring Partner.