National Hockey League Rules - Offside

In ice hockey, play is said to be offside if a player on the attacking team enters the offensive zone before the puck (unless the defensive team brings the puck into their own zone). A violation occurs when an offside player touches the puck. If a player crosses the line ahead of the puck but his team is not in possession of it, the linesman will raise his arm to signal a delayed offside; when all players from the offside team leave their offensive zone ("tag up" in the neutral zone) the linesman washes out the delayed call. When an offside violation occurs, the linesman blows the play dead, and a faceoff is conducted in the neutral zone. During the 2004-05 lockout, the league removed the "two-line offside pass" rule, which required a stoppage in play if a pass originating from inside a team's defending zone was completed on the offensive side of the center line, unless the puck crossed the line before the player. The removal of the two-line offside was one of several rule changes intended to increase overall scoring, which had been in decline since the early 1990s. The only time a player may precede the puck into the attack zone with the puck behind in the neutral zone is if none of his teammates are in the attack zone and the player with the puck has control of the puck in the estimation of the linesman (e.g.-short-sticking/spin-o-rama).