The last, and arguably most important innovation, which would at last make American football uniquely "American", was the legalization of interference, or blocking, a tactic which was highly illegal under the rugby-style rules. Interference remains strictly illegal in both rugby codes. The prohibition of interference in the rugby game stems from the game's strict enforcement of its offside rule, which prohibited any player on the team with possession of the ball to loiter between the ball and the goal. At first, American players would find creative ways of aiding the runner by pretending to accidentally knock into defenders trying to tackle the runner. When Walter Camp witnessed this tactic being employed against his Yale team, he was at first appalled, but the next year had adopted the blocking tactics for his own team. During the 1880s and 1890s, teams developed increasingly complex blocking tactics including the interlocking interference technique known as the Flying wedge or "V-trick formation", which was developed by Lorin F. Deland and first introduced by Harvard in a collegiate game against Yale in 1892. Despite its effectiveness, it was outlawed two seasons later in 1894 through the efforts of the rule committee led by Parke H. Davis, because of its contribution to serious injury.