Brooks E. Harlow

Diara M. Holmes serves as co-chair of the firm's Tax-Exempt Organizations Practice. She counsels tax-exempt organizations, including large public charities; colleges, universities and other higher education organizations; foreign charities and their U.S. affiliates; associations; government instrumentalities; social welfare organizations; and religious organizations on a broad range of tax compliance and governance issues. She advises nonprofit and for-profit organizations on structuring a va...

Mustafa Ostrander is a top attorney recognized by Best Lawyers in the practice area(s) of Energy Regulatory Law. Mustafa, who practices law in Washington, District of Columbia, has been recognized since 2026. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which Mustafa is held by other top lawyers in the same geographic and legal practice area.

David is the managing partner of the Washington, D.C. office, as well as the co-leader of the Investment Management Group. Prior to joining Sullivan & Worcester, David was Special Counsel in the Washington, D.C. office of Gibson, Dunn & Crutcher. He previously served as Assistant General Counsel for Legislation and Investment Company and Adviser Regulation at the Securities and Exchange Commission and as Counsel to SEC Commissioner Aulana Peters.

David F. Levy is a top attorney recognized by Best Lawyers in the practice area(s) of Tax Law. David F., who practices law in Washington, District of Columbia, has been recognized since 2016. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which David F. is held by other top lawyers in the same geographic and legal practice area.

James N. Mastracchio is a top attorney recognized by Best Lawyers in the practice area(s) of Tax Law. James N., who practices law in Washington, District of Columbia, has been recognized since 2026. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which James N. is held by other top lawyers in the same geographic and legal practice area.

Christine M. Shiker is a top attorney recognized by Best Lawyers in the practice area(s) of Real Estate Law. Christine M., who practices law in Washington, District of Columbia, has been recognized since 2018. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which Christine M. is held by other top lawyers in the same geographic and legal practice area.

Siran is a partner in the firm’s State Attorneys General and Enforcement Actions & Investigations practices. As such, she advises clients on a wide variety of state and federal regulatory matters, with a special emphasis on state consumer protection laws, including matters involving consumer financial services, data security, advertising and marketing. A former Senior Assistant Attorney General, Siran uses expertise gained in public service to resolve issues with state investigators...

Daniel M. Jaffe is a top attorney recognized by Best Lawyers in the practice area(s) of Transportation Law. Daniel M., who practices law in Washington, District of Columbia, has been recognized since 2022. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which Daniel M. is held by other top lawyers in the same geographic and legal practice area.

Sean P. Schmergel has been consistently recognized as one the DMVs top divorce and family law attorneys, including by Washingtonian Magazine, Arlington Magazine, Super Lawyers and Best Lawyers. He began practicing divorce and family law over 22 years ago and has continued to hone his legal practice before the local courts, developing a reputation as a zealous and thoughtful family law advocate. A resident of Northern Virginia for over 36 years, Mr. Schmergel holds a genuine concern for the le...

Christopher Cestaro is a partner in the firm's White Collar Defense and Investigations Practice. Mr. Cestaro’s practice focuses on white-collar criminal matters, government enforcement actions, internal corporate investigations, due diligence reviews and compliance counseling. Mr. Cestaro’s unique experience includes more than eight years as a federal prosecutor focused on white-collar cases, three years working as a compliance counsel for a multinational oil services company and ...