Assistant Attorney General of the Antitrust Division Christine Varney announced her resignation on Wednesday, effective August 5.
As the Justice Department's top antitrust official since April 2009, Varney has presided over the reviews of mergers including NBC Universal-Comcast and Google's purchase of ITA Software. She will join the law firm Cravath, Swaine & Moore LLP according to a report from the Wall Street Journal.
“Christine Varney led the Antitrust Division with great distinction through a period when the department confronted a number of proposed mergers and other matters that could have led to higher prices, lower quality products and less innovation in a recovering economy," said Attorney General Eric Holder.
"There is no doubt that her tireless work helped protect consumers and businesses from anticompetitive conduct and preserved competition in America’s economy.”
Tech policy watchers were quick to question the impact of the move on the Justice Department's pending review of AT&T's proposed acquisition of T-Mobile USA, which has raised concerns about competition in the wireless market.
"We hope and expect that review will determine the deal is a clear violation of antitrust law that will harm consumers and damage a vital sector of the economy."
Cravath is known for antitrust work but Varney will likely be restricted from working on issues related to her former position. A group representing computer and communications industry firms argued President Obama's choice to succeed Varney would define his legacy on antitrust issues.
“The Obama administration’s antitrust legacy depends on its ability to appoint a new leader who can deliver on Varney’s promise to reinvigorate antitrust enforcement and resolve critical pending antitrust cases involving the tech and telecommunications industry," said Computer and Communications Industry Association president Ed Black.
“The Obama administration must look for a new chief antitrust cop who is committed to strong enforcement and not afraid to stand up to powerful, connected companies when the evidence is solid."
Varney was viewed as a tough antitrust regulator, blocking a planned merger between NASDAQ and NYSE among others. But she drew criticism for the lengthy duration of some of the conditions place on firms including Comcast, which will make them subject to scrutiny for years after the deal.