Mary Ellen Callahan


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Mary Ellen Callahan, Chair of Jenner & Block’s Privacy and Information Governance Practice, has unique and broad experience advising clients at the interface of privacy protection with cybersecurity and national security issues.  A nationally recognized privacy attorney with a decade and a half of outside counsel experience, she served as Chief Privacy Officer of the U.S. Department of Homeland Security from 2009 until August 2012.  She is a prolific writer and speaker on cutting-edge commercial privacy issues. She provides advice and counsel to an array of clients in industries that include media, public health and health care, manufacturing, online retail, government contracts, energy and other critical infrastructure sectors.

Since returning to private practice, Ms. Callahan has assisted over two dozen clients on privacy- and cybersecurity-related matters. Her work includes providing up-front guidance on establishing compliance programs that reflect privacy policy and industry best practices. She has counseled companies on data governance issues, including use of customer and advertising data. She has advised industry associations on future privacy issues and measures to address cybersecurity vulnerabilities. In the rapidly growing area of mobile privacy, she has advised and written on privacy best practices and evolving standards and approaches. She counsels frequently on the Children's Online Privacy Protection Act, the Video Privacy Protection Act, compliance with the European Union Data Protection Directive and the implications for businesses of the emerging White House Framework on Critical Infrastructure Cybersecurity. Ms. Callahan regularly advises clients on requirements and protocols associated with data breaches.

In 2015, Ms. Callahan was recognized by The National Law Journal as a “Trailblazer” in the regulatory and compliance area.  In 2013, she accepted the highest award in the privacy industry, the Privacy Vanguard Award, given by the International Association of Privacy Professionals. The award honors the privacy professional who has demonstrated outstanding leadership, knowledge and creativity in privacy and data protection. In 2011, she received the select Federal 100 Award, which recognizes individuals in government and industry who have played pivotal roles in the federal government information systems community. Ms. Callahan’s work on integrating cybersecurity, transparency and privacy at the Department of Homeland Security was cited as the reason for her Federal 100 recognition.  She is a prolific writer and speaker on privacy issues, including having testified before Congressional Committees numerous times in her capacity as Department of Homeland Security Chief Privacy/Chief FOIA Officer. Ms. Callahan has served as Vice-Chair of the American Bar Association's Privacy and Information Security Committee of the Antitrust Division; Co-chair of the Privacy Committee of the CIO Council, the principal interagency forum for improving agency practices related to the design, acquisition, development, modernization, use, sharing, and performance of Federal information resources; and Co-chair of the Privacy and Civil Liberties Subcommittee of the Information Sharing and Access Interagency Policy Committee. She is a Certified Information Privacy Professional/United States (CIPP/US).

Prior to joining the Department of Homeland Security in 2009, as a partner in the DC office of an international law firm, Ms. Callahan focused on privacy, security, data protection, consumer protection, and e-commerce issues across a wide variety of industries including retail, technology, entertainment, financial services, health care, telecommunications and government contracts. She advised businesses, including multinational companies, on a variety of privacy and information governance issues, including privacy and security policies; performed audits of clients’ privacy and security policies as related to relevant state and federal legislation and created and implemented requisite compliance strategies and programs; and drafted website privacy policies and terms of use. Ms. Callahan is also experienced as a litigator and has represented clients before federal administrative agencies, in federal and state courts in the District of Columbia and in federal courts in Virginia and New York.

She serves the firm as a member of the Diversity & Inclusion Committee and is a co-chair of the firm's Women's Forum Steering Committee.  Her pro bono legal work has included assisting in the development of privacy policies, terms of use and communications strategies for non-profit entities.

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