THE DEPARTMENT OF HOMELAND SECURITY is quietly broadening its efforts to curb speech it considers dangerous, an investigation by The Intercept has found. Years of internal DHS memos, emails, and documents — obtained via leaks and an ongoing lawsuit, as well as public documents — illustrate an expansive effort by the agency to influence tech platforms. The work, much of which remains unknown to the American public, came into clearer view earlier this year when DHS announced a new “Disinformation Governance Board”: a panel designed to police misinformation (false information spread unintentionally), disinformation (false information spread intentionally), and malinformation (factual...