Mary Jo White, the former top government securities law enforcer, is returning to Debevoise & Plimpton, the New York-based law firm where she previously headed its litigation department.
Ms. White, who announced plans in November to leave the Securities and Exchange Commission as its chairwoman, will serve as senior chairwoman of the law firm, focusing on counseling boards and representing clients on significant and delicate legal matters, including companies facing crises involving multifaceted government investigations and cases.
"I got a call at 12:01 on Jan. 20, asking me to rejoin the firm," said Ms. White, whose departure from the S.E.C. took effect on Jan. 19. "And since I had a speech in San Diego, I used that time on planes to decide whether I wanted to practice law again."
After deciding that she did, Ms. White said it was not difficult to choose Debevoise, which, she said, had "the pre-eminent white-collar practice and many of the finest lawyers and colleagues with whom I have ever worked."
After joining the securities commission in April 2013, Ms. White sought a stricter crackdown on securities violators, changing the agency's practice of allowing companies to neither admit nor deny wrongdoing. More than 80 companies were brought to account in trials or administrative proceedings.
One of her chief lieutenants in that effort, Andrew J. Ceresney, also rejoined Debevoise after serving with her as director of the S.E.C.'s division of enforcement.
When Ms. White assumed the top securities enforcement job, she had headed Debevoise's litigation department for 11 years. She is also the only woman to have served as the United States attorney in Manhattan.
During her years at the commission's helm, she ran into criticism that the commission was not doing enough to punish companies and executives whose actions had battered the economy and created the 2008 financial crisis.
In an interview, she defended the commission's enforcement, saying that its "aggressive, tough but fair" approach protected investors "while deterring misconduct in many sectors of the securities markets."
"We brought important cases against financial institutions, major companies and senior executives for violations relating to financial reporting violations, trading abuses, sales of complex financial instruments and Foreign Corrupt Practices Act violations, among others," she said.