What Is an 'Outside Influence' in Golf?

And What Happens When an Outside Influence Interferes With Your Ball?

Dog steals Paul Casey's golf ball during the 2012 Alfred Dunhill Links Championship
Hey, where's that outside agency going with that golf ball?. Ross Kinnaird/Getty Images

"Outside influence" is a term used in the Rules of Golf for things that cause your golf ball at rest to move; or cause your moving golf ball to deflect or stop moving; and that are not you, your partner, your opponent (in match play), your caddies, the equipment of any of the above, or wind or water.

We'll give more examples below of things that are and are not outside agencies, but first, note that for more than 100 years the term for this was "outside agency." "Outside agency" is what was used in the rule book through 2018. In the new edition issued for 2019 and going forward, however, "outside agency" was changed to "outside influence."

In explaining why that change of terminology was made, the USGA wrote that it was "(r)evised to use more common language and indicate more clearly when this term applies."

Definition of 'Outside Influence' in the Rules of Golf

The official definition of "outside influence," as written by the USGA and R&A and as it appears in the Rules of Golf, is this:

"Any of these people or things that can affect what happens to your ball or equipment or to the course:
"Any person (including another player), except you or your caddie or your partner or opponent or any of their caddies,
"Any animal, and
"Any natural or artificial object or anything else (including another ball in motion), except for natural forces."

What Happens When a Outside Influence Moves Your Ball?

The definition of outside influence is most pertinent in the rule book in two particular rules. First, "outside influence" is used in several places in Rule 9, but Rule 9.6 (Ball Lifted or Moved by Outside Influence) is directly on point. The Player's Edition of the rule book makes things pretty simple:

"If it is known or virtually certain that an outside influence lifted or moved your ball there is no penalty. The ball must be replaced on its original spot (which if not known must be estimated)."

And there's also Rule 11.1 (Your Ball In Motion Accidentally Hits Person or Outside Influence). There is typically no penalty to anyone, and the ball should be played as it lies after hitting an outside influence while the ball is in motion.

We've cited the condensed Player's Edition; golfers should always consult the Full Rules edition on usga.org or randa.org.

More Examples to Explain Outside Influences

Among the things that qualify as outside influences: a match referee, a marker (when the marker is not your partner or your opponent), an observer, a forecaddie.

Some more examples of things that are outside agencies:

  • A dog that scoops up your ball, a bird that flies away with it (both these things have happened more than once in pro tournaments), a squirrel that deflects it;
  • spectators;
  • members of the golf course's greenkeeping staff;
  • a stray golf ball played by a golfer on some other hole that comes bounding onto the hole you are playing;
  • objects being blown by the wind that then hit your golf ball.

The wind itself is not an outside agency, but for example, a tumbleweed blowing across the course is an outside agency. Or how about this one: Your ball comes to rest inside a plastic bag; the wind then blows the plastic bag, moving your ball. Ruling? Outside agency, because in this scenario the wind is not moving your ball, it's moving the bag, which is then moving your ball.

Equipment of yourself or your side in stroke play, or, in match play, yourself and either side in the match, is not an outside agency. That includes things such as the golf cart (whether motorized or a pull cart) and player's towels.