Ahead of the 2015/2016 season, the body responsible for reviewing the laws of football, the International FA Board (IFAB), has issued new guidance to match officials around the offside law. The two new points of guidance are an addition to the current interpretation of interfering with an opponent, but do not constitute a change in the Laws of the Game.
The additional IFAB guidance
A player in an offside position shall be penalised if he:
1. clearly attempts to play a ball which is close to him when this action impacts on an opponent or
2. makes an obvious action which clearly impacts on the ability of an opponent to play the ball.
1. “Clearly attempts to play a ball which is close to him when this action impacts on an opponent”. The first part of the guidance has three elements: clearly attempts to play a ball; close to him; and when this action impacts on an opponent and all three of these elements are required for an offside offence to be committed. Judgement should be based on the physical evidence of the movement and actions of the player in an offside position. Attacking players who clearly attempt to play a ball which is close to them, and in doing so clearly impact on an opponent's ability to play the ball, should be penalised.
2. “Makes an obvious action which clearly impacts on the ability of an opponent to play the ball”. The second part of the guidance has two elements and both an obvious action and impact are necessary for an offside offence to be penalised. Match officials will have to consider whether an obvious action by an attacking player in an offside position means that the opponent would need to delay his action to wait and see if the attacking player in an offside position touches or plays the ball, and/or, the opponent's movement or ball-playing options are clearly restricted by the movement and/or actions of the attacking player in an offside position.
"Clearly attempts": this wording is designed to prevent a player in an offside position who runs towards the ball from quite a long distance being penalised (unless he gets close to the ball).
"Close": is important so that a player in an offside position is not penalised when the ball goes clearly over his head or clearly in front of him.
"Impacts": applies to an opponent's ability (or potential) to play the ball and will include situations where an opponent's movement to play the ball is delayed, hindered or prevented by the offside player.
Source: IFAB/Premier League