Seligman began her career in the private sector as a partner at Williams & Connolly in Washington, D.C. Only shortly after joining the firm, she was assigned to assist partner Brendan Sullivan in representing Lt. Col. North before Congressional hearing and at his trial. Eleven years later, her more senior partner, David Kendall, President Clinton's outside counsel, asked for her assistance. She appeared with Clinton when he testified before the grand jury in the Monica Lewinsky scandal, and she spoke on his behalf before the Senate at the impeachment trial. Her other clients at Williams & Connolly included large media organizations such as CNN (in the Operation Tailwind matter), ABC, and occasionally the National Enquirer (which was primarily represented by Kendall).