As the United States attorney for the Eastern District of New York in the late 1990s, Mr. Carter oversaw the prosecution of police officers in connection with the brutal assault of Abner Louima, a Haitian immigrant — a case that would haunt the Police Department for years.

At a news conference in Lower Manhattan announcing the appointment of the city's new corporation counsel, Mr. de Blasio said Mr. Carter would be the point man on two of the biggest legal issues facing the incoming administration: the stop-and-frisk litigation and the Central Park Five case.

The mayor-elect said that once in office, he will drop the city's appeal of a federal judge's ruling in the stop-and-frisk lawsuit and will settle claims by the men who were wrongfully imprisoned in connection with the rape of a Central Park jogger.

It will be up to Mr. Carter to provide the "legal architecture" to carry out those plans, Mr. de Blasio said.

Mr. Carter will replace Michael A. Cardozo, who has been corporation counsel through all three of Mayor Michael R. Bloomberg's terms and has been a forceful champion of many of the administration's initiatives.

The job is one of the busiest in city government, and Mr. de Blasio said it "touches literally every part of government and, therefore, the lives of every New Yorker."

"It requires toughness, conscience and a fundamental commitment to the rights of every New Yorker," he added.