wedge principle.The principle that an act is wrong in a specific instance if, when raised to a general level of conduct, it would injure humanity.

“[T]here is the familiar argument from the ‘wedge principle,’ which is used to deny the possibility of looking at particular circumstances in applying moral rules.” Glanville Williams, The Sanctity of Life and the Criminal Law 315 (1957).
[Blacks Law 8th]