Any club, other than a putter, can be a maximum 48 inches in length, but this would be limited to 46 inches if organizations such as the PGA and European Tours use the option of a new “model local rule” being introduced by the R&A and United States Golf Association.
Mickelson, 51, used a driver that was listed as 47.9 inches long when he won the US PGA Championship at Kiawah Island in May. He branded the proposed rule change as “pathetic” in a tweet two months ago.
The move is part of the R&A and USGA’s “distance insights” project aimed at limiting the distances golf balls travel in the modern game.
At the recent Ryder Cup, DeChambeau smashed a drive 417 yards to leave a 72-yard second shot at the par-five fifth hole at Whistling Straits. The 2020 US Open champion, 28, then finished seventh at the Professional Long Drivers Championship in Las Vegas.
He has used a 45.5-inch driver on tour but used a 48-inch version at the long driving competition.
It will be up to the main tours and organizers of leading amateur events to choose whether to introduce the new regulation.
“We believe this is the right thing for the game at this time,” said R&A chief executive Martin Slumbers.
“It will provide tournament organizers with the flexibility to choose for themselves within the framework of the rules.”
The change was initially considered in 2016, two years after research began into the impact that clubs longer than 48 inches had on distance.
Announcing the rule change, Slumbers said: “We have taken time to consult fully with the golf industry, including players, the main professional tours and equipment manufacturers, and have considered their feedback carefully.
“We are working hard to maintain an open, collaborative and considered dialogue with these key stakeholders as we continue to evolve the equipment standards rules to ensure they reflect the modern game.”
Mike Whan, chief executive officer of the USGA, said: “Admittedly, this is not the ‘answer’ to the overall distance debate/issue but rather a simple option for competitive events.
“It’s important to note that it is not a ‘Rule of Golf,’ and as such, it is not mandated for the average, recreational golfer. Rather, this is an available tool for those running competitive events.”
