An unusual complication of Kocher's manoeuvre.

the same time (two players of the attacking team, the last two players of the defending team, and the ball), and this may not be compatible with the normal eye function—especially as these five objects can be anywhere within the defenders’ half of the pitch, an area of at least 3200 m. This may explain at least some of the instances when television replays of a game clearly show that the offside rule was not properly implemented. The key factor in applying this rule correctly is that the player in question must be in the offside position at the exact time when the ball is passed from a teammate, not when the player receives the ball or when the ball is en route between the players. By reviewing the physiology of the eye movements likely to be involved in assessing an offside position, I have shown that the relative position of four players and the ball cannot be assessed simultaneously by a referee, and unavoidable errors will be made in the attempt. The use of modern technology during games—freeze frame television and frame by frame analysis—is advisable to limit these errors.