Electronic Line Calling in Tennis: Why Line Judges Are Disappearing
No more line judges and no more challenges at most big events. Here is how electronic line calling took over tennis.
For decades, tennis relied on line judges in crisp uniforms calling balls in or out. Today, at most of the sport's biggest events, those calls come from cameras. Here is how electronic line calling (ELC) works and why it took over so fast.
How It Works
A set of high speed cameras around the court tracks the ball in three dimensions. Software calculates exactly where the ball lands and, if it is out, plays a recorded voice call such as "Out!" or "Fault!" within a fraction of a second. The chair umpire stays in charge of the match, but no longer has to overrule close calls.
From Challenges to Live Calls
The technology first arrived as a challenge system in the mid 2000s. Players could appeal a human call and watch a replay on the big screen. The newer version, often called live electronic line calling, makes every call automatically, so there is nothing to challenge.
Who Uses It
- US Open and Australian Open: both moved to electronic line calling on their courts in 2021.
- ATP Tour: adopted electronic line calling at all tour level events starting in 2025.
- Wimbledon: replaced line judges with ELC in 2025, a historic change for the most traditional event in tennis.
The Clay Court Exception
The French Open has kept human line judges. On clay, the ball leaves a mark, and the umpire can climb down from the chair to inspect it. Many clay events still trust that method, although some have experimented with cameras.
The Pros
- Accuracy: far fewer missed calls on the fastest serves
- Speed: no stoppages for challenges
- Consistency: the same standard on every court, not just the main stadium
The Cons
- Lost jobs and tradition: line judges had been part of the sport for over a century
- Rare glitches: when a system fails, there is no backup human on the line
- Atmosphere: some fans miss the drama of a challenge
The Bigger Picture
Tennis is part of a wider trend across sports. Baseball now uses an ABS challenge system for balls and strikes, and Formula 1 relies on sensors and cameras to police track limits. Learn more about the majors in our Grand Slams guide.
Background from Wikipedia
Hawk-Eye
Hawk-Eye is a computer vision system used to visually track the trajectory of a ball and display a profile of its statistically most likely path as a moving image. It is used in more than 20 major sports, including baseball, cricket, tennis, badminton, hurling, rugby union, soccer, Gaelic football, American football, and volleyball.
The Sony-owned Hawk-Eye system was originally developed in the United Kingdom by Paul Hawkins. The system was first implemented in 2001 for television broadcasts, where it was used to analyze leg before wicket decisions in cricket.
Text from Wikipedia, CC BY-SA 4.0
Frequently Asked Questions
Does Wimbledon still use line judges?
No. Wimbledon replaced line judges with electronic line calling in 2025, ending a tradition that had lasted nearly 150 years.
Why does the French Open still use line judges?
On clay, balls leave a visible mark, so umpires can inspect the mark to settle close calls. Roland Garros has kept human line judges for that reason.
Can players still challenge calls in tennis?
At events that use live electronic line calling, there is nothing to challenge because the system makes every call automatically. The old challenge system is used only where human line judges remain.
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