Ms. Callahan was appointed Chief Privacy Officer and Chief Freedom of Information Act Officer (FOIA) by Department of Homeland Security Secretary Napolitano in March 2009. Created by Congress in 2002, the Department's Privacy Office is the first statutorily mandated privacy office in any federal agency, whose mission is to preserve and enhance privacy protections for all individuals, to promote the transparency of Homeland Security operations, and to serve as a leader in the federal privacy community.

In her role as Chief Privacy Officer, Ms. Callahan is responsible for evaluating department-wide programs, systems, and technologies and rule-makings for potential privacy impacts, and for providing mitigation strategies to reduce any privacy impact. She and her staff have extensive expertise in privacy laws, both domestic and international, that help inform privacy policy development both within the Department, and in collaboration with the rest of the federal government. Her office also advises senior leadership to ensure that privacy protections are implemented throughout the Department.

Ms. Callahan also serves as the Department's Chief FOIA Officer; her office centralizes both FOIA and Privacy Act operations to provide policy and programmatic oversight and support implementation across the Department.

Prior to joining the Department, Ms. Callahan was a partner with the law firm of Hogan & Hartson (now Hogan Lovells), where she specialized in privacy and data security law.

She is a frequent author and speaker on privacy issues. In 2008, Chambers and Partners selected her as a “Band 1” privacy and data security lawyer in the United States.  She serves as vice-chair of the American Bar Association's Privacy and Information Security Committee of the Antitrust Division. And now as Chief Privacy Officer, she co-chairs both the CIO Council's Privacy Committee, and the Information Sharing Environment Privacy Guidelines Committee.

Ms. Callahan holds a Juris Doctor from the University of Chicago Law School and graduated magna cum laude from the University of Pittsburgh. Prior to law school, Callahan worked at the Congressional Research Service of the Library of Congress as part of the Special Task Force on the Development of Parliamentary Institutions in Eastern Europe.