Stuart Hammer is the head of the firm’s Environmental Practice Group and a member of its Corporate Department. For more than 25 years, he has advised private equity firms and corporations on environmental issues in mergers and acquisitions, financings, securities offerings and other transactions. He has counseled clients on the environmental risks associated with hundreds of transactions involving facilities in the United States and overseas. Mr. Hammer also advises private equity firms and other investors on environmental, social and governance (ESG) issues, including ESG issues associated with their investments.

Mr. Hammer is consistently ranked as a leading lawyer in environmental law. He is noted as a top-tier lawyer for the Environment: Mainly Transactional category by Chambers USA (2023), in which clients laud him as “a solid practitioner who understands the nuances of transactions, understands site conditions and regulatory compliance elements across multiple industries, and strives to meet client expectations in a timely manner.” In previous editions of the guide, he has been described as “an amazing resource for complex environmental matters” and “a consummate professional who brings well-rounded knowledge and sharp analytical skills to his clients.” He is singled out for his “ability to understand complex environmental history and use this to inform his advice and practical understanding of the risks.” He is said to be “a leading light in environmental law,” “top-notch,” “a commercial, practical and surgical practitioner, as well as a good listener” and “very thorough and extremely timely.” He has also received praise from clients for his “effective knowledge and good communication. Mr. Hammer is also recognized as a Leading Lawyer in The Legal 500 US (2023) and listed in its Hall of Fame. The guide notes that he is “very knowledgeable, responsive, and accessible.” Clients have said he “brings a clear passion to his work” and “helps clients understand and mitigate risk.” He is recognized as a leading environmental lawyer by Best Lawyers in America (2023) and Who’s Who Legal (2022). Additionally, The National Law Journal (2017) lauds Mr. Hammer as a Trailblazer for Energy & Environmental.

Mr. Hammer has written extensively on environmental and ESG issues, including “INSIGHTS: How to Successfully Evaluate Environmental Risks During a Pandemic,” Bloomberg Law (June, 2020); “Don’t Ignore The Smoke Signals,” Private Funds Management (February, 2017); “Climate Change Related Laws in the U.S. — What to Expect Under the New Administration,” LexisNexis Japan Business Law Journal (February, 2017); “New Administration’s Environmental Policies Unlikely to Undermine Investor ESG Focus,” Pensions & Investments (January 20, 2017); “Greener Pastures,” Private Equity International (December 26, 2016); “Weighing Pros And Cons Of EPA's Audit Policy,” Law360 (April 1, 2015); “How Companies Can Manage Environmental Reputational Risk,” Business Ethics (April 9, 2014); “Climate Change Disclosure,” NACD Directorship (July 26, 2011); “Climate Change Disclosure Obligations for Insurers,” Insurance Law360 (February 11, 2011); “Effects of EPA Clean Air Initiatives,” Environmental Law360 (December 2, 2010); “What to Know in the Absence of a Climate Change Law,” Environmental Law360 (August 11, 2010); “The NAIC Produces Revised Climate Change Risk Disclosure Survey,” The Debevoise & Plimpton Financial Institutions Report (June, 2010); “Climate Change Issues Are Turning Up the Heat on Businesses in the U.S.,” The Debevoise & Plimpton Private Equity Report (Winter 2010) (reprinted in Private Equity Manager (April, 2010)).

Mr. Hammer is a regular contributing author to Debevoise’s Private Equity Report, writing most recently in the Private Equity Report: 2023 Outlook (January 2023). He also wrote the environmental chapter of the 2021 Healthcare Mergers and Acquisitions Answer Book (Practicing Law Institute, October 2020).

Mr. Hammer joined Debevoise in 1992. He received his B.A. magna cum laude from Yeshiva University in 1988 and his J.D. from Cardozo Law School in 1992.


  • Yeshiva University, Benjamin N. Cardozo School of Law, 1992, J.D.
  • Yeshiva University, 1988, B.A.

Bar Admissions

  • New York