It has been 10 years since Hawk-Eye changed tennis for the better, 10 years since Jamea Jackson made the first official challenge of a line call — albeit unsuccessful — during a singles match in Miami.

A traditionalist by instinct, I was skeptical of the whole enterprise, fearing that electronic line judging would remove some of the drama and human interest from the game. Nor did I like the new inequities. With Hawk-Eye installed only on the main show courts at the elite tournaments, hoi polloi playing in the hinterlands would not get the same digital access.

But I was wrong. Electronic line judging actually added entertainment value, giving fans a rooting interest and quick resolution while giving players increased peace of mind in a head game of a sport that still has plenty of other ways to drive you crazy.

As for the inequities, they were worth the trade-off. And didn’t Indian Wells’ owner, Larry Ellison, a man with pockets deeper than the Mariana Trench, even decide to have the system installed on all his tournament’s courts?

Yet 10 years later, when even low-tech football has finally adopted some elements of replay, there remains one Grand Slam holdout where line calls are still made the old-fashioned way.

At the French Open, as in all clay-court tennis, the umpires, not the machines, still have the last word. They descend from their chairs — just as they did in the days of tennis trousers and under-the-table payments to amateurs — to settle points of contention by examining the marks in the clay with a player usually close by to discuss the evidence.

Archaeology, my colleague Alexander Wolff once called it. But it remains an inexact science. Chair umpires sometimes spot the wrong mark in the clay, which, according to the television analyst Rob Koenig, happened at least twice at the tournament in Rome this month.

“I’m a big proponent of them using Hawk-Eye on clay,” Koenig said Monday. “It’s still very accurate and within a millimeter or two of the actual mark. What it does help eradicate is the big miss from the umpire.”

Some other players and former stars agree.

“I think you should just have Hawk-Eye, maybe not on all the courts but maybe on the main ones,” said Nick Kyrgios, the combustible young Australian who had some disagreements over marks in his first-round victory over Marco Cecchinato at Roland Garros on Sunday. “There has been a couple of calls in the last couple weeks that have been really close.”

Ion Tiriac, the mustachioed Romanian who owns the clay-court event in Madrid, has lobbied unsuccessfully to use Hawk-Eye in recent years. But the French Open has never seriously considered it, just as the sport did not seriously consider it when it adopted electronic line calling on other surfaces in 2006.

“On clay, it’s easy, there is the mark, and it’s easy to see if the ball is in or out,” Jeremy Botton, the French Open’s new chief executive, said in an interview on Monday. “It’s also a point of difference, which we like. I don’t see why we’d change it.”

As reassuring as those marks in the clay appear, they do not always tell the whole story. That is because the mark depends not only on where the ball lands but also on the condition of the clay where it lands.

“If it’s dry and windy and blown away on top, it’s going to leave a smaller mark than the actual landing of the ball,” said Gayle David Bradshaw, the executive vice president for rules and competition at the ATP. “And then if there’s some extra clay, the explosion makes the mark larger than what the actual contact of the ball was.”

That raises one of the more persuasive points in favor of the status quo. Using Hawk-Eye on clay might be more accurate, but it could make for plenty of awkward moments when the mark and the electronic ruling are not in accord.

“You get on a clay court where the marks vary due to the conditions, and there’s just a greater risk there’s going to be discrepancies that can lead to discussion or doubt,” Bradshaw said. “It kind of comes down to what is sellable. The mark is sellable to the player. What they see is what they believe.”

Balls leave marks on hardcourts, too, but players put less stock in their reliability. Though Hawk-Eye has cooled tempers on cushioned acrylic and grass, it risks inflaming them on clay. In some cases, it is doing so already with television broadcasters using the system at the French Open as an analytical tool for their coverage. It has been installed on the two main courts: Philippe Chatrier and Suzanne Lenglen.

The players do not see the Hawk-Eye reviews while on court at Roland Garros, but they sometimes get a look at them eventually. “I have seen pictures, seen the Hawk-Eye, and it’s actually in,” Kyrgios said.

According to Peter Irwin, Hawk-Eye’s director of tennis, the system installed in Paris is “exactly the same system” installed elsewhere. Though it is being used for second-guessing on television, Irwin said that the system had not been optimised for official use and that it had never been officially tested on clay by the game’s governing bodies.
One of the issues is the shifting clay-court surface.

“One thing that’s integral to our system is we measure the court, but we also measure the undulations in the ground,” Irwin said. “So when you play on clay, obviously the ground is constantly changing, so that would require a lot more work from our side. We would constantly have to recalibrate the system if it were to be used for officiating.

“On a hardcourt, we do it once at the start of the tournament because the surface doesn’t change. On grass, we do calibrate constantly throughout, but clay is just a lot more change.”

According to Irwin, it would take about 30 minutes of maintenance work after each match on court to put the system back in peak working order, a delay that would be a problem with a busy Grand Slam order of play.

The good news: Clay dust swirling through the air on a blustery day does not affect the system’s accuracy, according to Irwin. Neither does rainfall, which players often play through on clay, or clay piling up on a line during a rally.

“Unless someone builds a sand castle on court, we’re good,” Irwin said.

But there are other stumbling blocks. Hawk-Eye costs upward of $40,000 per court to install. On clay, there is also the risk of creating a two-track challenge system unless you provide the system to every court. Otherwise, on the outside courts, players would still be challenging the traditional way.

“So do you allow the chair umpire to come down off his chair only two or three times?” Bradshaw asked. “Do you put the same Hawk-Eye rules on challenge limits out there? If you didn’t, the guys would want to be playing outside without limitations.”

As in archaeology, the deeper you dig into the matter, the more complexity seems to appear.

For now at least, it seems best to leave the old ways and fresh marks undisturbed. Then again, I was wrong about Hawk-Eye the first time.