Originally: John Morton’s (supposed) method of levying forced loans by arguing that those who were obviously rich could afford to pay, and those who lived frugally must have amassed savings (hist.). Hence in extended and allusive use: a practical dilemma, esp. one in which both of the choices or alternatives available disadvantage or discredit the chooser.
“Morton’s Fork, n.” OED Online. Oxford University Press, December 2016. Web. 7 March 2017.