Campbell made a controversial call in 1939 when refereeing a game involving the Toronto Maple Leafs when defenceman Red Horner was struck with a stick and Campbell doled out only a minor penalty, even though Horner was bleeding.
Campbell se je po tekmi zavedal svoje provokativne geste in oddal le zelo prizanesljivo poročilo o incidentu, NHL predsednik Frank Calder je tako Clapperju naložil le denarno kazen.