Used successfully now in tennis also, as well as cricket & rugby. Has been used in racing - horse & greyhound - for god know how long; why, 'photo-finish' is a dead metaphor. & everyone wonders what we ever did without it, and feels ripped off when watching games on an out-court, or at one of the minor tournaments, where "Cyclops" or "Hawkeye" aren't available.

So of course it will come in football. With, it is to be hoped, the sensible sort of restriction. e.g. as to be used only by ref & his assistants, or on request for limited # of appeals by manager or captain only [as, mutatis mutandis, in tennis - only 3 unsuccessful appeals per set].

It could work perfectly well; and is surely bound to come; and there will be no more idiocy like that goal awarded to Chelsea the other night when Gomes made yet another cock-up in Spurs' goal; but every commentator & commenter agreed that it hadn't crossed the line & the Asst ref couldn't conceivably have seen from where he was anyhow.

~Michael~