“For some months,” the document begins, “representatives of the FBI and of the Department of Justice have been formulating a plan of action for an emergency situation wherein it would be necessary to apprehend and detain persons who are potentially dangerous to the internal security of the country.” If the U.S. faced a rebellion, an invasion (real or threatened), or an “attack upon United States troops in legally occupied territory,” the government would suspend habeas corpus and detain everyone on an index that “contains approximately twelve thousand individuals, of which approximately ninety-seven per cent are citizens of the United States.”
It sounds like the ramblings of a paranoid crank. And that’s exactly what it is, except the crank in question was J. Edgar Hoover, head of the Federal Bureau of Investigation, in a 1950 letter to the White House. The proposed plan was very real, and the letter describing it was declassified in December. It can be found in the latest volume of The Foreign Relations of the United States, a series published by the U.S. State Department, and it can be downloaded at state.gov/r/pa/ho/frus/truman/c24687.htm.
There’s no evidence that the Truman White House took Hoover’s proposal seriously. Interestingly, a decade earlier, when the previous president supported a different plan to round up Americans without regard for due process, Hoover had argued for their civil liberties. Those internees were Japanese Americans imprisoned during World War II, and Hoover’s protests were ignored.