Baker McKenzie announced Monday that Mark Hamer, a former partner and global chair of the firm’s antitrust and competition practice, is returning to the law firm after a year of public service at the U.S. Department of Justice.

Hamer served as Deputy Assistant Attorney General in the DOJ’s Antitrust Division from March 2025, joining the leadership team under Assistant Attorney General Gail Slater. During his tenure, he helped lead one of the most active periods in civil antitrust enforcement in U.S. history, overseeing investigations and litigation in technology, healthcare, entertainment, agriculture, real estate, and financial services.

“Mark was a valued colleague and leader at our firm, and we are thrilled to welcome him back,” said Colin Murray, Baker McKenzie’s Americas CEO. “His recent DOJ experience will provide unmatched insight for clients navigating complex antitrust litigation and regulatory challenges.”

Hamer reflected on his time at the DOJ in a LinkedIn post, describing it as “the privilege of a lifetime” to work alongside Slater’s leadership team. He called 2025 a “high-water mark for civil antitrust enforcement,” highlighting that the division handled the largest docket of civil antitrust matters in its history.

Before rejoining Baker McKenzie, Hamer had served as the firm’s global chair of antitrust and competition since 2020 and previously held the position of North American chair. His prior experience also includes nearly seven years as a trial attorney in the DOJ’s Antitrust Division and a partnership at DLA Piper before joining Baker McKenzie in 2016.

Creighton Macy, the current global chair of Baker McKenzie’s antitrust practice, praised Hamer’s extensive experience in both government and private practice, saying it will strengthen the firm’s global team. The practice now has approximately 340 practitioners across more than 60 offices in over 40 countries.

“Mark will fit seamlessly into the practice he helped build,” Macy added. “We look forward to leveraging his expertise to help clients manage increasingly complex litigation and regulatory risks, both in the U.S. and internationally.”

Hamer said that after a year of public service, he felt the timing was right to return to private practice and continue advising clients on antitrust matters. He emphasized that his experience at the DOJ gave him a deeper understanding of enforcement priorities, which he intends to apply to support clients navigating evolving competition law challenges.