Matthew Huppert A Justice Department trial attorney who helped represent the government in its ad technology monopolization fight against Google has joined Winston & Strawn LLP's Washington, D.C., team.

Matthew Huppert joined Winston & Strawn's litigation department and its antitrust and competition practice as a partner, the firm announced Monday. Huppert helped answer U.S. District Judge Leonie M. Brinkema's questions related to how quickly Google could sell its advertisement exchange, AdX, to have a meaningful impact on competition.

A Columbia Law School graduate, Huppert started his legal career at what is now Kellogg Hansen Todd Figel & Frederick PLLC. He spent seven years there, and then joined the Justice Department in 2021, according to his LinkedIn profile.

In 2023, he served as a counsel to the assistant attorney general and head of the DOJ's Antitrust Division, Gail Slater, who stepped down from her role last month.

A number of former Justice Department attorneys who helped challenge alleged monopolization practices by Google have left the government for private practice. Diana Aguilar, who was a first-chair trial team member of the government antimonopoly litigation case against Google, joined O'Melveny & Myers LLP just this week.

Huppert told Law360 Pulse in an interview Tuesday that he served as a counsel to Slater for a few months, before moving back to work on the Google ad tech case.

And while some attorneys have told Law360 Pulse they feel there's currently a lack of respect for career, public servant prosecutors at the DOJ, Huppert said that hadn't played into his decision to leave.

Huppert wanted to join the DOJ to get more trial experience, something he "very much did," he said. But his plan had always been to stay working for the government no longer than five years.

"Certainly, the work experience for the folks at DOJ has changed a lot in the last year. Policies have changed, enforcement priorities have changed, but the Antitrust Division is still the Antitrust Division," Huppert said. "There's a lot of great lawyers there who I hope to maybe be across the table from at some point soon, but there's a core of dedicated public servants at the Antitrust Division who I very much respect, and I hope that that stays as it is today."

Reflecting on his work at the Justice Department, Huppert noted he recused on the Google ad matter late last year, and he declined to comment specifically on the challenges associated with that litigation.

Huppert said that he joined the Justice Department as a litigator, but that he learned how to be a trial lawyer, throughout his public service experience. For example, he helped represent the government in its challenge of Assa Abloy's purchase of Spectrum Brands' hardware and home improvement business, and helped oversee trial teams in the government's challenge to JetBlue's purchase of Spirit Airways.

"I think that litigating those cases was very formative for me, but I think what I learned at the government was how to use what you have available to you, efficiently," Huppert said. "We don't always have the biggest team, we often have a much smaller team than the teams we're litigating against at the government — obviously that's different in private practice."

Huppert said his move to private practice, and specifically Winston & Strawn, was motivated by joining a platform full of "litigators' litigators," meaning that work is a core focus of the firm and its culture.

Huppert was impressed by the depth of trial expertise at the firm, which includes several of his former colleagues from the DOJ's Antitrust Division, like Benjamin L. Rudofsky and Joshua Hafenbrack, who also worked with him at Kellogg Hansen, he said.

"They're friends of mine and longtime colleagues, so it's fun to get to work with them and have that personal connection," he said.

Several members of the firm's leadership said in statements Monday that they were looking forward to Huppert's contributions to the team, including Winston & Strawn's litigation department co-chairs, Linda Coberly and Brett Johnson. They said in a joint statement his enforcement insight and litigation experience "add a valuable dimension to the firm's client counseling and business development aptitude."

David Rogers, managing partner of the Washington, D.C., office, said in a statement, "Matt's recent experience with the DOJ adds to our market leadership in core practices and aligns seamlessly with our growth objectives."