Wimbledon ditches human line judges for electronic line calling

The Wimbledon Championships, the most prestigious of professional tennis events, declared it would no longer use human line judges at next year’s tournament. In 2025, the London event will use an electronic line-calling system (ELC) instead.

First reported in The Times of London, the announcement marks a radical change to a 147-year-old tradition, albeit one that’s on trend with the sport’s broad shift toward technology-assisted officiating. In 2023, the Association of Tennis Professionals announced all of its events would move toward automating line calls, and two of the four Slams have already incorporated it. With Wimbledon going with ELC, the last holdout is the French Open.

In the past, a court was monitored by as many as nine line judges, each tasked with determining if a ball is in or out in their assigned lane. According to the same The Times article, Wimbledon employs 300 judges covering over 600 matches during the two-week event. But the embrace of computer systems is not reflective of a desire to reduce manpower (the automated system still requires a lot of people in a booth). Instead, ELC systems are believed to improve accuracy — a belief widely held especially among players not named Jelena Ostapenko.

Last month, I published a story about the history of electronic line calling in tennis, focusing on the most popular implementation, Hawk-Eye Live. The technology, which uses a system of ten to twelve cameras around the court, actually determines where a ball will land depending on its trajectory. Originally, Hawk-Eye was introduced as a fun accessory for broadcasts to show line calls rather than a guidance for officiating. But after an infamous 2004 US Open match between Serena Williams and Jennifer Capriati revealed a number of obviously erroneous calls — to a large TV audience at home, no less — the organizing bodies of tennis moved to deploy Hawk-Eye as a tool that could be used by players to challenge line judges. Two decades later, Hawk-Eye calling is so dependable that it is automated at the US Open; players don’t even have to ask for it now.

During a match, ELC systems capture huge swaths of data: not just the ball at 70 frames per second of every second of a match, but also the player movements as well. This provides a lot of stats for broadcasters during the match, as well as a wealth of information back to the players to assess their performance after. But there’s perhaps a less expected, and more lucrative, use case as well: selling that data to sports betting companies.

There’s an entire pipeline of data and licenses that allows apps like DraftKings or FanDuel to derive betting odds from a ball- and player-tracking system, and it also enables organizations like the Association of Tennis Professionals to profit from the booming sports betting industry indirectly. (Some level of obfuscation is required — making money directly from gambling could compromise the integrity of the sport.) In my reporting, I learned that the Association of Tennis Professionals makes as much money from licensing ball and player tracking data as it does selling its broadcast rights. Wimbledon will likely make a pretty penny too, once it moves to an ELC system next summer.

As a spectator, I have personally started to miss the days when Hawk-Eye was used as a challenge system rather than an automated source of officiating. If a player felt confident that a line judge was wrong, they could dispute it. The chair ump would summon Hawk-Eye, and through a dramatic build up — for the officials, the players, and the audience — the location of the ball would be revealed, and a call upheld or overturned. The result could change the course of a match. Personally, I find it hard to resist such great drama!

We still have forms of this in other sports. Is anything more fun than when an NFL coach drops a red flag to contest whether a wide receiver had control of the ball? But whereas the rules of professional football still have shockingly squishy ideas of what a catch is, things are more rigid in tennis. A ball is either in or it’s out. And as the sport moves toward a technological solution to make its officiating decisions, soon line judges will be out too.