In many ball sports there is always some argument as to whether the ball crossed a line, whether it be for a goal, a point or out of play, whatever, this idea could be adapted. Why not have an aerial wire set into the side lines or court markings on your chosen field. A transponder set inside the ball would allow the officials not only to tell if the ball had crossed the line but also where. This would come into its own in football primarily, the aerial could then send a signal to a row of LED's set atop the adsvertising boards around the pitch so the palyers know exactly where to take the throw in from, with none of that "take tens steps up the field" shinanaggins. The transponder would have to be set in the centre of the ball or have more than one, set around it's circumference.-- LardyBloke, Nov 12 2001 Fault-line monitors have been used at Wimbledon for several years.-- angel, Nov 12 2001 Haven't there been plans for using electronic tags or radio transmitters in "soccer" balls, primarily for checking if it goes over the goal line, to avoid embarrassments like Geoff Hurst's famous 2-goal hat-trick against West Germany in 1966.-- pottedstu, Nov 12 2001 [angel], I didn't realise that earthquakes were a problem in South-west London!-- lewisgirl, Nov 12 2001 There never seems to be a problem with throw-ins in rugby. Maybe it's because they have more competent officials. Most referees aren't capable of using a whistle properly let alone complicated electronics! My preferrred solution though, is to do away with the sidelines altogether and have the side walls/advertising hoardings as part of the pitch so that you can use them for five-a-side style deflections.-- DrBob, Nov 12 2001 Arena football (armored rugby) is just that [DrBob]. It is an indoor version that is sweeping the States. Been to a game, lots of fun.-- barnzenen, Nov 12 2001 random, halfbakery