How many calls came into question during the recent World Cup competition in South Africa? In just about every competitive sport, referees must call who crossed the line first, or if the ball was inside or outside of a line. Many sports have addressed the issue. Tennis uses a Hawk-Eye technology that films and replays the ball play in question. Cycling uses cameras on the finish line and transponders on each bike. Football draws a digital line in the replay to measure the ball and distance it’s traveled. More technology is on the way.