Rory McIlroy’s shocking finish at the second men’s major wasn’t the only thing that made the headlines. Following the USGA test, the Northern Irishman’s “non-conforming” driver news spread around the golf world like wildfire. Naturally, everyone expected him to explain—only for Rory McIlroy to storm out of Quail Hollow after his 4th round finish. However, the question remains—how do the tests happen, and are they fair?

The CT test serves as a sophisticated yet rapid field assessment to check if a driver’s face is overly springy. It measures face flexibility in microseconds, with the legal limit set at 239 microseconds and an 18-microsecond tolerance, resulting in a maximum allowable limit of 257 microseconds. Think of it like a speed limit on a highway: just as drivers must stay within a certain speed to ensure safety, golf clubs must adhere to specific limits to maintain fairness in the game. Sure, the golfers need to keep it fair, but are the governing bodies doing the same?

The rules have frustrated the six-time PGA Tour champion, Lucas Glover, who couldn’t help but discuss the subject on SiriusXM PGA Tour Radio. “We’re not all playing under the same umbrella at these majors, unless we did test everybody. So we got LIV guys, we got other tour guys, we got tons of different players and tours being represented at the four biggest tournaments of the year. So why doesn’t everybody get tested at every major? And why don’t we somehow try to make sure it’s the driver being used. We should all be held under the same rules at these events. Everybody should be tested for equality, if we’re going to have all of these tours and all of these people coming together.”

Lucas Glover’s points are valid. Throughout the year, officials regularly test drivers at PGA Tour events and major championships to check if they exceed limits, with about a third of players selected for testing each week. The USGA may also test additional driver heads stored in tour equipment vans. During the 2025 PGA Championship, the PGA of America requested the testing, and PGA officials controlled how they shared the results with players and the media.

Other golfers likely failed the test as well, but there’s no way to confirm it. So, why doesn’t the USGA test every player’s driver if they are committed to the issue? Although the test is quick, events typically have only one technician available, making it nearly impossible to manage testing for 156 players. However, if officials decided to make driver testing mandatory, they could make it happen.

However, considering the gravity of the situation, Glover isn’t the only one demanding fairness in driver testing. After finishing his final round at the PGA Championship, Xander Schauffele made a similar remark: “I think they should test everyone’s driver. It’s not right to just test 50 guys. It just doesn’t make sense if you’re in it for the spirit [of the game].” Schauffele pointed out that by not testing everyone, the officials were failing to protect the entire field. His sharp comment partly stems from the “non-conforming” driver situation he faced in 2019.

The 2019 British Open incident that “pissed off” Xander Schauffele

In 2019, Xander Schauffele faced a difficult situation when a random R&A test revealed that his driver failed. He expressed his frustration by saying, “I had a little bit of run-in with them, because they only test 30 players. I thought it was a little bit unfair.” He made it clear that he was willing to comply, stating, “I would gladly give up my driver if it’s not conforming. But there’s still 130 other players in the field that potentially have a nonconforming driver as well.” Talking about the same at the 2025 PGA Championship, Schauffele said, “That pissed me off.”  This underscored his concerns about the fairness of the testing process.

The governing body of the Open Championship tested 30 random drivers for compliance, including one from Tiger Woods. In 2018, R&A chief executive Martin Slumbers mentioned that none of the drivers violated testing limits, which measure the spring-like effect of the driver clubface through the CT Test. After Schauffele’s driver failed, Callaway CEO Chip Brewer accepted the company’s responsibility. Schauffele was the only player to publicly disclose his failed test and raised his concerns with The R&A, suggesting, “What’s the fair thing to do? Just test the whole field. It’s plain and simple.” Schauffele also blamed PXG’s driver; however, the brand denied any such accusations, pointing out that Billy Horschel’s driver passed the test.