An unfortunate misunderstanding when responding to a motion to dismiss a procedurally complicated case triggered a forfeiture rule and knocked out Len and Joanne Boogaard’s lawsuit against the National Hockey League for allegedly contributing to the overdose death of their son Derek.The Boogaards started with a state court complaint in Chicago that alleged the NHL violated the requirements of a substance abuse program it negotiated with the players’ union. Removing the litigation to federal court, the league …