A defensive system, sometimes confused with the neutral-zone trap, that sees a forward drop back with the defense when the opposing team breaks out of their own zone and the other two forwards on the ice forecheck and force the other team toward the side. This eliminates odd-man rushes and produces turnovers so the left-wing-locking team can counter-attack quickly.
In the National Hockey League - NHL the most famous team to first employ this style of play was the Detroit Red Wings under the direction of legendary coach Scotty Bowman who had witnessed the style played in Europe.
Although it is called the left-wing lock, the forward dropping back does not always have to be the left wing. The defensive setup allows teams to force turnovers by always having a third player back with the defenseman, thus allowing the defenseman to try and force turnovers and quickly counter attack.