Electronic line calling (ELC) is a camera-based system that decides whether a ball is in or out, replacing the human line judges who used to make those calls. At ATP Tour level it is now used at every tour-level event on every surface, and Wimbledon adopted it for all its match courts from 2025. A separate system, video review, lets the chair umpire check other kinds of decisions on a screen.
Here is how the two technologies work, where they are used, and what they mean for players and fans.
What electronic line calling does
ELC tracks the ball with cameras positioned around the court and calls “out” and “fault” automatically, in real time. Where it is used, there are no line judges on court: the system handles all the line calls that they used to make.
The key difference from older challenge systems is that the call is made live. Under the older model, line judges made the call and players could challenge a limited number of decisions, with a replay then shown to the crowd. With live ELC, every line call comes from the system, so there is nothing to challenge on the lines.
Where it is used
The ATP Tour
The ATP announced in 2023 that it would adopt electronic line calling across the tour from 2025, with the stated aim to “optimise accuracy and consistency across tournaments.” When the ATP outlined its plans for the 2025 season, it confirmed that “for the first time ever, all tour-level events on all surfaces are featuring Live Electronic Line Calling.”
Wimbledon
In October 2024 the All England Club announced that it would replace line judges with electronic line calling at the 2025 Championships, on all Championships and qualifying match courts. The decision followed testing during the 2024 event.
Explaining the move, chief executive Sally Bolton said the club considered “the technology to be sufficiently robust and the time is right to take this important step.” She added: “For the players, it will offer them the same conditions they have played under at a number of other events on tour.”
Other events
Use at other tournaments depends on the organiser and the surface, so the picture can vary from event to event and between the ATP and WTA calendars.
What video review covers
Line calls are only one part of officiating. Other decisions, such as whether a player reached a ball before its second bounce, are made by the chair umpire. Video review gives the umpire a replay to check those calls.
According to the ATP, video review was introduced on every court at all nine ATP Masters 1000 tournaments in 2025, starting at the BNP Paribas Open in Indian Wells in March. It allows the chair umpire to review:
- not-up calls (whether the ball bounced twice before it was played);
- foul shots;
- touches (whether a player touched the ball, the net or was hit by the ball);
- hindrances;
- scoring errors;
- possible default situations.
The technology has a longer history at the season’s showpiece events. Video review made its ATP Tour debut at the Next Gen ATP Finals in 2018 and was first used at the Nitto ATP Finals in 2020.
Line calling versus video review at a glance
| Electronic line calling | Video review | |
|---|---|---|
| What it decides | In or out, and faults on serve | Not-ups, foul shots, touches, hindrances, scoring errors, possible defaults |
| Who makes the decision | The system, automatically | The chair umpire, using replays |
| When it happens | Live, during the point | After the point, when a decision is reviewed |
| Replaces | Line judges | Nothing; it supports the umpire |
When replays still cause controversy
Technology has not removed every dispute. Two recent examples from the Asian swing show how reviews and replayed points still shape matches.
At the China Open in Beijing, Coco Gauff stopped play during her win over Sun Xinran after LED lights on the advertising boards flickered, and requested a video review. The umpire ordered the point to be replayed, which drew boos from the crowd.
At the Shanghai Masters, two of Taylor Fritz’s points were replayed in his match against Stefanos Tsitsipas after a ball fell from his pocket while he was serving at 2-5 in the third set.
Both cases turned on distractions during a point, the kind of decision that rests with the umpire rather than the line-calling system.
What it means for fans
For spectators, the most visible change is the absence of line judges and of the old ritual of players challenging calls. Matches flow with fewer interruptions on the lines, while the debates that remain tend to centre on the umpire’s judgement calls, such as hindrances and replayed points, rather than on whether a ball clipped the line. Knowing which decisions belong to the system and which belong to the umpire makes those moments much easier to follow.
Frequently asked questions
Can players still challenge line calls?
Where live electronic line calling is in use, the system makes every line call, so there are no line judge decisions to challenge.
Are there still line judges in professional tennis?
Not at ATP tour-level events or on Wimbledon’s match courts, where electronic line calling has replaced them. Practice can differ at other events.
Does the chair umpire still matter?
Yes. The umpire runs the match, applies the rules, enforces time limits and makes the judgement calls that video review is designed to support.
Does electronic line calling work on clay?
The ATP says live electronic line calling is used at all tour-level events on all surfaces, which includes clay.
New to the sport? Start with our guides to how tennis rankings work and the Wimbledon final set tie-break rule.
Sources: ATP Tour, All England Club, Al Jazeera.
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