It is about the assassination of United States President John F. Kennedy and takes issue with the investigatory methods and conclusions of the Warren Commission.

[4][5] The title of the book was taken from Lord Chancellor Thomas Erskine's defense of James Hadfield, who had attempted to assassinate King George III in 1800.

[3] According to Alex Raskin of the Los Angeles Times, "Rush to Judgment opened the floodgate for Kennedy assassination conspiracy theories".

[6] Bertrand Russell, who is thanked in the acknowledgements section of the book for being "kind enough to read the manuscript and make suggestions",[7] set up the Who Killed Kennedy?

[16][17] Some of the assassination witnesses who present their observations on-camera include Nelson Delgado, James Tague, Charles Brehm, Mary Moorman, Lee Bowers, Sam Holland, Jim Leavelle, James Simmons, Richard Dodd, Jessie Price, Orville Nix, Patrick Dean, Napoleon Daniels, Nancy Hamilton, Joseph Johnson, Roy Jones, Harold Williams, Penn Jones, Jr. and Acquilla Clemons.