Stroke interference
Any positioning that would not allow the opponent to use a normal stroke. This especially applies to a player moving in too close and being hit by, or restricting the follow-through of, the player hitting the ball.
Interpretation
A player hitting the ball is entitled to stroke the ball without being in danger of contacting an opponent during the stroke. The stroke includes the back-swing as well as the follow-through of the arm. If a player is contacted during any part of the stroke by the player hitting the ball, an avoidable hinder should be called, assuming the player who was hit could have avoided the interference with reasonable effort. This interference might not have affected the shot, but it doesn’t matter if the ball reaches the front wall or not. This avoidable hinder must be called for safety reasons. Playing too close can cause serious injury, and the referee should forfeit the offending player if this type of positioning continues.