Interference and obstruction are an inevitable aspect of this highly athletic sport, where two players are confined within a shared space. Generally, the rules entitle players to reasonable access to the ball, a reasonable swing and an unobstructed shot to any part of the front wall. When interference occurs, a player may appeal for a 'let' and the referee (or the players themselves if there is no official) then interprets the extent of the interference. The referee may elect to allow a 'let' and the players then replay the point, or award a 'stroke' (either a point or the right to serve) to the appealing player, depending on the degree of interference and whether the player interfered with was likely to have hit a winning shot had the interference not occurred.
When it is deemed that there has been little or no interference, the rules provide that no let is to be allowed, in the interests of continuity of play and the discouraging of spurious appeals for lets. Because of the subjectivity in interpreting the nature and magnitude of interference, the awarding (or withholding) of lets and strokes is often controversial.
When a player's shot hits his or her opponent prior to hitting the front wall, interference has occurred. If the ball was travelling towards the side wall when it hit the opponent, it is usually a let. However, it is a stroke to the player who hit the ball if the ball was travelling straight to the front wall when the ball hit the opponent.