Why Do Officials Use Hand Signals? Communicating a Decision to Everyone at Once

An official has to convey a decision to players who may be a hundred metres away, to a crowd that is loud enough to make speech useless, to colleagues who need to coordinate, to a scorer who must record it and to a broadcast audience watching without commentary. Speech fails on almost every count, and a public address announcement is too slow and too dependent on equipment. A visual signal from a person whose position is known solves all of it at once, provided the signals are visible at distance, distinguishable from one another, distinguishable from ordinary movement, and few enough to be learned. Those constraints are what shape the vocabulary, which is why signals tend to use the whole arm rather than the hand, why they are held rather than flicked, and why each sport's set is small.

A single decision usually carries several pieces of information delivered in sequence:

• •That play has stopped, generally with a whistle rather than a gesture
• •What the offence was, which is the distinctive part of the signal
• •Who committed it, frequently by pointing or by indicating a number
• •What the consequence is, including the direction of the restart
• •Whether a sanction applies, which cards and other devices communicate
• •In some sports, a formal report to a scorer separate from the field signal

The systems grew up separately and their differences are historical rather than principled. Cricket's signals are addressed primarily to the scorers and are held until acknowledged, which is why they are deliberate and unhurried compared with sports where the signal is for the players. American football signals were standardised for broadcast and stadium audiences and are elaborate enough to specify the offence, the number of the offending player and the yardage. Association football uses a very small vocabulary, on the principle that the direction of a free kick and a card cover nearly everything, with additions arriving slowly and contentiously. The card system itself was invented for the 1970 World Cup by an English referee who wanted to communicate a caution across a language barrier, and it spread to dozens of other sports afterwards, which is a rare case of a signal whose origin is precisely documented.

A separate and less visible layer of communication runs between the officials themselves. Assistant officials on the touchline use flag positions that encode information for the referee rather than for anyone else, with the height and side of the flag indicating who the restart favours and where it should be taken. Radio communication between officials became standard in top-level competition from the late 1990s and changed the work substantially, allowing discussion before a decision rather than independent judgement, and it is now taken for granted in sports where it was once controversial. Hidden signals exist too, including discreet indications between officials about who is covering what, and prearranged gestures that let one official tell another something without informing the players. That layer is what makes a crew work as a unit rather than as several people watching the same event.

The introduction of video assistance added new communication problems and new signals to solve them. Officials now need to indicate that a review is under way, which is why the gesture outlining a rectangle appeared, and they need to indicate the outcome afterwards. The delay between an event and a decision breaks the immediacy the whole system was built on, leaving crowds uncertain for a minute or more, which has prompted announcements over the public address explaining the decision in several competitions, reversing the original reason for using gestures at all. Some sports have added microphones so officials explain decisions directly to broadcast. The result is that the signal is no longer sufficient by itself in the sports that have gone furthest, and the system is being rebuilt around explanation rather than instantaneous indication.

Gestures convey a decision to distant players, a loud crowd, colleagues, scorers and broadcasters at once, which speech cannot do. The constraints of visibility and distinguishability explain why signals use the whole arm and why each sport keeps the set small. Video review broke the immediacy, prompting spoken announcements that reverse the original reason for signalling.