Deborah Feinstein, former director of the Bureau of Competition at the Federal Trade Commission. (File: 2013) Photo by Diego M. Radzinschi/THE NATIONAL LAW JOURNAL

After nearly four years as the Federal Trade Commission’s top antitrust enforcer, Debbie Feinstein is returning in September to Arnold & Porter Kaye Scholer, where she will lead the global antitrust group, the firm said Wednesday.

“Arnold & Porter is home, and so it just seemed like the natural place to go back to. I worked there when I was a summer associate, and then when I was an associate,” Feinstein said in an interview Wednesday. “Then, after I went to the FTC, I came back to Arnold & Porter. It’s just always been a terrific antitrust group going back decades upon decades upon decades.”

Indeed, Feinstein found a landing spot at Arnold & Porter following an earlier stint at the FTC. After two years as an associate at Arnold & Porter, she left in 1989 to become assistant director to the bureau of competition. In 1991, she returned to the firm as an associate, rising to partner in 1995. From 2010 to 2013, she led Arnold & Porter’s U.S. antitrust group.

“It took me 20 years to move two doors down the hall, but it was worth the wait,” she said, referring to the two decades separating her initial role at the FTC and her 2013 appointment as chief of the agency’s competition bureau.

Feinstein, whose tenure as the FTC’s top antitrust enforcer was marked by litigation victories against Sysco Corp.’s proposed acquisition of US Foods and Staples’ bid to buy rival Office Depot, returns to the private sector at an uncertain time for the commission. Only two of the FTC’s five commissioner seats are currently filled, and it is unclear whether President Donald Trump will install the acting chairwoman, Maureen Ohlhausen, to the top post in a permanent capacity.

Feinstein said that, “unless something extraordinarily dramatic happens,” the FTC’s antitrust enforcement will be “business as usual.”

“Much of the day-to-day work is done by the staff, and they have a tried-and-true method of analysis and ways they investigate. That’s just not going to change,” she said. “There’s also been remarkable continuity over the years in terms of antitrust enforcement. You’ve seen it even in the last month or two in terms of what the agency is doing.”

Feinstein becomes the latest high-ranking lawyer to rejoin Arnold & Porter following a stint in the federal government. In early June, veteran antitrust prosecutor Bill Baer began anew as a partner at the firm. Baer most recently served as third-in-charge at the Justice Department, where he was previously assistant attorney general for antitrust. In the late 1990s, he led the FTC’s competition bureau.

“Debbie is universally regarded as one of the leading antitrust lawyers in the country. Her expertise in mergers, antitrust litigation, and counseling uniquely position her to help clients navigate compliance with antitrust laws here and around the world,” Baer said in a prepared statement Wednesday. “No one works harder, has better judgment, or is as highly respected by enforcers than Debbie Feinstein.”