There are five specific actions a player is not allowed to take if doing so improves any one of the conditions affecting the stroke. Before looking at what the prohibited actions are, we need to look at what it means to actually improve a condition affecting the stroke:

Meaning of Improve

The Rule that protects the conditions affecting the stroke only prohibits players from making those areas better. If you make your situation worse, the Rules don’t penalize you – but you’re stuck with the changes. In order to determine when you have made the situation better the Rules specifically define what it means to improve.

If you alter one or more of the conditions affecting the stroke, or if you alter other physical conditions that might affect play outside of the CATS so that you gain a potential advantage, you have improved the conditions. This means that it doesn’t matter whether you actually get the benefit of your actions, if the changes you make have the potential to give you an advantage the condition has been improved.

Prohibited Actions

Of the five prohibited actions mentioned at the top, two of these actions can be fixed before the stroke is made, but the other three cannot be undone:

Fixable

• Move, bend or break any fixed natural or artificial object or a tee-marker when playing from that teeing area. Growing things like trees and bushes, or artificial fixed objects like immovable obstructions or boundary objects are all part of playing the game and you cannot remove their interference from your conditions affecting the stroke. But if you make the mistake of moving them, you can avoid penalty if you put the object(s) back before making the stroke.

• Move a movable object into place. This is generally specific to building a stance, such as moving a bench into place so you can stand on it to play a ball in a tree or putting a pile of pine needles on your line of play to serve as a bumper for your putt.  But again, if you make this mistake, you can undo it by removing the moved objects before making the stroke.

Not Fixable

• Alter the surface of the ground. This could happen in a number of ways. If you replace a divot or remove or press down already replaced divots or create or eliminate other holes, humps or bumps on the ground that could affect your play, then you’ve altered the surface and will be penalized if doing so improved the conditions affecting the stroke.

• Remove or Press Down Sand or Loose Soil. Sand and loose soil are not loose impediments and may not be moved if doing so improves your conditions affecting the stroke.

• Remove dew, frost or water. If there’s a temporary accumulation of water, there’s a Rule for that. But dew and frost are just something that happen on a golf course and you can’t remove it if it improves your conditions affecting the stroke, such as mopping up dew on your line of play on the putting green.

If you take any one of these actions and doing so improves one or more of the conditions affecting the stroke (and is not fixed), then you get the general penalty (loss of hole in match play or two strokes in stroke play). But also see the Allowed Actions for when you will not get a penalty.