As chief legal officer, Littleton leads a department of approximately 150 lawyers and legal professionals. She oversees all legal matters related to regulatory proceedings, commercial transactions, litigation, labor, employment, the environment, benefits, cyber, and privacy. As corporate secretary, Littleton also leads the corporate-governance function.

Littleton was responsible for the transactional work and regulatory approvals required for the spin-off of Exelon’s generation and retail businesses in 2022. She negotiated the buy-back of Électricité de France S.A’s interest in Constellation Energy Nuclear Group, which owned interest in several of Exelon’s nuclear plants. Littleton also led the company’s response to Commonwealth Edison’s deferred prosecution agreement, including related Department of Justice and Securities and Exchange Commission investigations, regulatory proceedings, and securities, consumer-fraud, and derivative litigation.

Prior to joining Exelon in 2020, Littleton was co-chair of the Investigations, Compliance and Defense Practice at Jenner & Block LLP. Littleton was Chambers USA-ranked in white-collar investigations and was named on Global Investigations Review's list of 100 "Women in Investigations" globally. She served on Jenner's Management Committee and co-chaired the firm's Women's Forum Steering Committee, comprised of women partners across offices.

Before joining Jenner, Littleton was an Assistant U.S. Attorney with the Department of Justice for over a decade, serving in the Northern District of Illinois in Chicago and in the Northern District of Florida. Littleton is a former law clerk to the Honorable Gerald W. Heaney of the U.S. Court of Appeals for the Eighth Circuit, and a former law clerk to the Honorable Joseph L. Tauro of the U.S. District Court for the District of Massachusetts.

Littleton is a member of the Exelon Foundation Board of Directors. She also is the executive sponsor of The Forum for Executive Women and the Network of Exelon Women. 

Active in the greater Chicago community and nationally, Littleton co-chairs the Chicago General Counsel Forum and is on the Board of Directors of the Illinois Holocaust Museum. She is a member of the Association of General Counsel, the Edison Electric Institute’s General Counsel Forum, the Economic Club of Chicago, Cornell Law School Dean’s Advisory Council, and the Stetson University College of Arts & Sciences Advisory Board. Littleton also is active with Legal Counsel for Legal Diversity and has made the organization’s Leaders-on-the-Front pledge.

Littleton received her law degree, magna cum laude, from Cornell Law School and her Bachelor of Arts degree from Stetson University.