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Sean M. Bigley

Managing Partner, Bigley Ranish, LLP

Sean M. Bigley is a national security attorney and managing partner of Bigley Ranish, LLP.  Mr. Bigley’s practice primarily encompasses defending federal employees and contractors in security clearance denial cases. He also provides personnel security consulting to major international defense and aerospace corporations, and prosecutes intelligence community whistle-blower retaliation cases.

Since first opening his firm in 2013, Mr. Bigley has grown it from a solo practice to a five-attorney partnership with employees in three states. Bigley Ranish, LLP attorneys regularly appear before administrative tribunals at agencies ranging from the CIA to the Department of State, representing in excess of 200 American intelligence officers, diplomats, armed forces personnel, and other security clearance holders each year around the world.  In 2016 alone, Mr. Bigley and his colleagues represented clients in roughly forty states and a dozen countries.

The idea for this unique practice was borne out of Mr. Bigley’s prior service as a federal background investigator.  Prior to and during law school, Mr. Bigley was an investigator for the U.S. Office of Personnel Management, where he conducted some of that agency’s most sensitive security investigations in the Los Angeles metropolitan area. Mr. Bigley has also served on the faculty of Chapman University, teaching national security and criminal justice courses with an emphasis in U.S.-European security cooperation. Earlier in his career, Mr. Bigley worked for several years in the White House and Department of Homeland Security under President George W. Bush.

A recognized expert in national security law, Mr. Bigley’s commentary on the topic is frequently sought by major media outlets such as Fox News, The New York Times, and CNN. He is a contributing writer for Clearancejobs.com and GovExec.com.

Mr. Bigley earned his Juris Doctorate from Chapman University School of Law.  He holds a Bachelor’s Degree from Washington D.C.’s American University and a Master’s Degree from Boston University. 


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Publications and Multimedia
Presidential Nominees and Foreign Influence: Mitigating National Security Risks
Federalist Society Review, Volume 18
January 18, 2017