In soccer, the rule says that impending an opposite player to reach the ball when the ball is not within a playing distance is a foul. To be precise, the obstruction rule was replaced by the “impending the progress rule” in 1997. Technically, there is no obstruction rule, although we keep calling it that.
Soccer Rules - Fouls - Obstructing or Impeding. In any sport, a foul is a violation of that sport's code of conduct, and each sport punishes foul play in its own unique way. Soccer defines a foul as an unfair action a player commits against an opposing player or the opposing team during the course of a match.
For some time now, the rule of obstruction has been active in soccer but it doesn’t exist in the game anymore. Obstruction in soccer is now known as the act of impeding an opponent’s movement or progress, meaning that a player deliberately moves into his opponent’s path to force a change of direction, obstruct, slow down or even block when he doesn’t have the ball in playing distance.
The FIFA rule book still has obstruction listed as a reason for a foul. FIFA Law 12 – Fouls and Misconduct clearly states that an indirect free-kick should be given if a player impedes or obstructs an opponent.
Here's the rule-book definition, found in Definitions (obstruction): Obstruction is the act of a fielder who, while not in possession of the ball and not in the act of fielding the ball, impedes the progress of any runner.
3. There are quite a few things that happen in a football match that go uncalled. For example, many times a goal keeper handles the ball for more than 6 seconds, or a throw in is not taken from the place where the ball left the field of play, etc. One of the most misunderstood of these is impeding. That’s right…impeding…not obstruction.
The Obstruction rule actually doesn't exist in the rules of the game anymore and is now called "impeding the progress of an opponent". It basically means moving into the path of the opponent to obstruct, block, slow down or force a change of direction when the ball is not within playing distance of either opponent.
As they both move toward the goal line, following the ball, the center decides the defender is not within playing distance of the ball, whistles, and calls obstruction, awarding an indirect to the attacking team.