What is offsides in hockey? Explaining rules, meaning and how it’s determined on the ice

In hockey, a game can be defined by pure inches. That's especially the case at the blue line, where the margin between a scoring chance and a dead play is as thin as the edge of a skate blade. It is a boundary that demands perfect timing and absolute precision, yet it remains one of the most debated and scrutinized territories on the ice.

In the high-stakes environment of the Olympics or NHL, where games are won or lost on single sequences, this invisible line becomes a battleground for coaches, officials, and the technology designed to catch what the human eye simply cannot. There's a rule that everyone dreads: offsides.

Take Team USA's first Olympic game against Latvia, for example, where a Brock Nelson goal in the first period was overturned because the play was ruled offside. There are plenty of defining moments in recent years in the NHL, including Cale Makar’s controversial "non-offside" goal against the Oilers in the 2022 Western Conference Final. In that instance, the goal was upheld because Makar technically didn't have "possession" as he crossed the line, allowing his teammate to tag up in a split-second window.

Offsides. It can win and lose a game, and as Herb Brooks said in "Miracle": "It's a game of inches."

Here's everything you need to know about the offsides rule.

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What is offsides in hockey?

In hockey, the offside rule is a puck-first policy designed to prevent players from waiting near the opponent's goal for a long pass. A play is ruled offside if an attacking player crosses the blue line into the offensive zone before the puck does.

Remember that all offsides reviews happen because this wasn't called lol pic.twitter.com/dTaW6nZMWO

To stay onside, a player must ensure that at least one skate is touching the blue line — or is at least over the "plane" of the line —at the moment the puck completely crosses into the zone. If a player enters too early, they must tag up by retreating and touching the blue line with their skate before they can legally rejoin the attack.

While the rule sounds simple, modern technology has turned it into a game of pixels; coaches can now challenge goals to see if a player's skate was a fraction of an inch off the ice before the puck arrived.

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Hockey offsides rules

Here is the breakdown of how the rule works in the NHL and International (Olympic) play:

1. The Golden Rule
   1. A play is offside if both skates of an attacking player completely cross the leading edge of the blue line before the puck does. To stay onside, a player must have at least one skate touching the blue line (or the "plane" of the line) at the instant the puck fully crosses it.
2. The "Plane" of the Line
   1. A major rule change in recent years (now standard in the 2026 Games) is that a player’s skate does not have to be physically touching the ice to be onside. As long as the skate is in the air above the blue line, they are considered onside.
3. Delayed Offside
   1. If the puck is dumped into the zone while teammates are already inside, the linesman will raise their arm to signal a delayed offside. The attacking players must all retreat and "tag" the blue line with their skates simultaneously. Once everyone has cleared the zone or touched the line, the offside is negated and they can go back after the puck.
4. The "Possession" Exception
   1. If a player has clear possession and control of the puck (e.g., skating backward with the puck or stick-handling), they are allowed to precede the puck across the blue line. This is why you will sometimes see a player cross the line before the puck without a whistle.

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Hockey offsides review for goals 

If a goal is scored, a coach can challenge the play if they believe the attacking team entered the zone illegally at any point during that specific possession. In the scenario where a coach challenges, the refs and NHL office will review the play.

For a goal to be overturned, the offside must have occurred on the initial entry that led to the goal. If the puck leaves the zone and comes back in legally after an offside was missed, the goal stands. Moreover, there needs to be clear enough evidence to overturn the decision.

If the challenge is successful, the goal is taken off the board. If it is not, then the coach loses his challenge and the opponent is given a minor penalty.

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When was offsides added to hockey rules?

The modern offside rule was born out of a chaotic "scoring explosion" during the 1929–30 NHL season.

While hockey had various rules about passing since its inception, the specific "blue line offside" we know today was established in December 1929 to fix a mistake the league had made just months earlier.

Since that original 1929 decision, the rule has been tweaked several times to keep up with the speed of the game:

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What is a blue line? 

In simple terms, the blue lines are the boundaries that divide the hockey rink into three distinct sections. They are the most important markings for determining the flow of the game and, specifically, the offside rule. 

Both teams' offensive zones are marked by the blue lines, with the red line at the center. This splits the rink into three zones: 

• Defensive zone: The area between your own goal and the first blue line. 
• Neutral zone: The 50-foot "middle ground" between the two blue lines. Where the center-ice logo is located.
• Offensive zone: The area between the opponent's blue line and their goal.

The blue line is considered part of whichever zone the puck is currently in. If the puck is in the offensive zone, the blue line is "offensive ice" — meaning the puck isn't out until it completely clears the line.

For defensemen, the blue line is their primary workstation. They try to keep the puck inside the offensive zone. If the puck slides back over the blue line into the neutral zone, it is out, and every attacking player must leave the offensive zone before they can bring it back in.

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Offsides in hockey vs. soccer

While both hockey and soccer use offside rules to prevent "goal hanging" (players standing near the opponent's net to wait for long passes), the mechanics of how they are triggered are very different. In hockey, the rule is tied to a fixed line on the ice, whereas in soccer, the "line" is mobile and tied to the last defender.

In hockey, the blue line never moves. It doesn't matter where the defenders are standing; if the puck is in the neutral zone, you cannot cross that blue line until the puck does. The rule is judged the moment the puck crosses the blue line. If you are already in the zone when it crosses, you are offside.

In soccer, the "offside line" is an invisible line that moves up and down the pitch with the defenders. A player is in an offside position if any part of their body is nearer to the opponents' goal line than both the ball and the second-to-last opponent (usually the last outfield defender, with the goalkeeper being the first). Additionally, offsides isn't called until after the ball is kicked.

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