Stanley Mullen's "Fool Killer" (short story, justice, free): Do you _really_ want impartial & logical justice?
Notes.Author clarifies the title near end: "The Fool Killer never has to kill; it is enough if the fools know he is present, ready to strike, to keep them on their toes, make good citizens of bad, or at least careful citizens of those inclined to heedless cruelty or stupidity."
Fact sheet.First published: Astounding, May 1958.
Download full text as part of the scans of Astounding (British ed), August 1958.
Among the stories from Astounding/Analog issues edited by John Campbell.