He writes about security and civil liberties for Bloomberg News, and previously worked for The Intercept reporting on classified documents leaked by former National Security Agency contractor Edward Snowden.
[2][3] In August 2014, Gallagher revealed the existence of ICREACH, an NSA search engine that he alleged is "the largest system for internally sharing secret surveillance records in the United States.
"[4][5][6] In March 2014, with Glenn Greenwald, he revealed a joint NSA and British Government Communications Headquarters program to infect millions of computers with malware,[7] a report that prompted Facebook founder Mark Zuckerberg to personally call U.S. President Barack Obama to complain.
[8][9][10] In 2013, Gallagher was threatened by a private security contractor while working on a story exposing the use of facial recognition technology at the Statue of Liberty in New York.
[11][12][13] He is listed on the New America Foundation's website as a Future Tense Fellow under a program that seeks "to bring exceptionally promising new voices and ideas into the nation's public discourse.