Golf's two governing bodies released a clarification Wednesday on the rule aimed at keeping caddies from being able to help their players line up a shot.
The rule now says a two-shot penalty for his caddie standing behind him can be avoided if a player backs away from his stance and starts over anywhere on the golf course. Previously, the penalty could only be avoided on the putting green.
The rule also says caddies won't violate the rule if they were not aware their players were stepping in to take their stance.
"Experience has taught us that introducing a new rule requires us to balance patience with a willingness to act quickly when necessary," said Thomas Pagel, the senior managing director of governance for the USGA.
The clarification was a quick response to a two-shot penalty on Denny McCarthy at the Phoenix Open, which later was rescinded so the rule could be studied. McCarthy's incident followed another case a week earlier on Li Haotong in Dubai.
Rule 10.2b was created because of longtime criticism that caddies were helping to align players on shots. The rule stated that caddies could not deliberately stand behind their players as they were starting to take their stance until the shot was hit.
Li's caddie was behind him on the 18th green in Dubai as Li stepped into to take his stance. He was penalized two shots, which dropped him from a tie for third to a tie for 12th, and the R&A supported the decision because it followed the letter of the rule.
McCarthy's case was more complicated. He faced a 70-yard shot over water and was casually swinging the club away from the ball as his caddie stood behind him. Even though McCarthy backed away to take his stance, he initially was penalized because it did not occur on the green.
Once the PGA Tour noticed several other examples that could be cited, it took back the penalty for more study.
By clarifying what is deliberate, the USGA and R&A have allowed exceptions when it's clear the player is not trying to gain an advantage.
Among the examples cited by the USGA and R&A were a caddie who was raking a bunker and was in a direct line behind the player; and a caddie standing behind as the player walks over to tap in a putt. It also says caddies could stand behind a player while holding an umbrella until it's time to hit the shot.
Under the clarifications, caddies can line up their players for the purpose of making sure their club won't hit a tree, or their feet are not on a cart path.
The new rule was effectively immediately.