What ruling applies when a player in an offside position receives a header from an opponent?

When a player in an offside position receives a header from an opponent, it is considered legal play because the ball was last played by an opponent. The Laws of the Game state that a player cannot be offside simply by being in an offside position; they must gain an advantage from it when the ball is played by a member of the opposing team. Since the header is a deliberate act by the opponent, the offside rule does not apply in this situation, allowing the play to continue without a stoppage for offside. Consequently, the player in the offside position is not penalized, and the game continues as normal.