By Mack Reynolds (1917-83) and Fredric Brown (1906-72).
First appearance: Galaxy, January 1951.
Reprinted many times (HERE).
Short short story (8 pages).
Online at Archive.org (HERE).
(Note: Possibly objectionable language in common use then.)
"Justifiable homicide is a solidly established point of law, but the justification for murder depends on where the killer lives . . . and when!"Whether we like it or not, the future is coming. In the case of Lou Allenby and his sister Susan, when the future does arrive, bringing with it a truth they both find absolutely unacceptable, there's only one way Lou can think of to deal with it—murder . . .
- We wonder if Reynolds and Brown were influenced by Richard von Coudenhove-Kalergi's Practical Idealism (1925; HERE); since then, however, the opposite has been proposed (HERE).
HERE) and, in his capacity as a crime fiction writer, Fredric Brown (HERE).
The bottom line:
I pray you, in your letters,
When you shall these unlucky deeds relate,
Speak of me as I am; nothing extenuate,
Nor set down aught in malice: then, must you speak
Of one that lov'd not wisely but too well . . .
— The Moor