Electronic Line Calling in tennis is an extension of the previously used Hawk-Eye system, whereby ten cameras and over 20 personnel monitored line calls via animated replays and triangulation. However, ELC is an upgraded system as calls are made in real-time rather than produced through a replay.

An electronic line judge is a device used in tennis to automatically detect where a ball has landed on the court. Attempts to revolutionize tennis officiating and the judging of calls in the sport began in the early 1970s and has resulted in the design, development and prototyping of several computerized, electronic line-judge devices.

Since 2022, the U.S. Open has had no line judges. Instead, the tournament uses Hawk-Eye Live, an electronic line-calling system, to determine whether a tennis shot is in or out. Electronic line-calling has been around tennis since the 1980s, dating back to Cyclops, a system used during Wimbledon to judge if a ball was in play or not.

The ATP announced Friday that it will use Electronic Line Calling Live — known as ELC Live — for all “out” calls in all matches beginning two years from now. Each match still will be overseen by a chair umpire but the line judges who used to be entrusted with determining where shots landed will no longer be present on court.