Junior Mendes' crucial second goal for St.Mirren on Saturday prompted a heated debate on the Message Board - was it onside or not? With John Potter behind the line, Clyde technically only had one player between Mendes and the goal-line. But was Potter still interfereeing with play? Here is the official response sent to the website from the Referees Association's Instructional and Publications Committee...
Thank you for your query on the offside law transmitted to our Head Office.
A similar question was answered by FIFA as follows:
"If a defending player moves beyond his own goal line to place an opponent in an offside position, the referee allows play to continue and cautions the defender when the ball is next out of play."
From your explanation the second rearmost defender (John Potter) was still in active play, despite being behind the goal line, and could clear the ball from the goal line if a shot was made. His purpose of being there was to try and prevent a goal being scored against his team. Therefore, the referee should have permitted play to proceed.
Chairman I&P Committee
From this explanation we can finally conclude that the linesman's decision was in fact correct on Saturday.