You may watch NHL games and wonder why a sport with so much violence can have a penalty for hitting a player too viciously into the boards. Well, its okay to hit opposing players in this manner sometimes, but it has to be done within the rules.
The NHL Rulebook states boarding as follows:
"A boarding penalty shall be imposed on any player who checks or pushes a defenseless opponent in such a manner that causes the opponent to hit or impact the boards violently or dangerously. The severity of the penalty, based upon the impact with the boards, shall be at the discretion of the Referee. There is an enormous amount of judgment involved in the application of this rule by the Referees. The onus is on the player applying the check to ensure his opponent is not in a defenseless position and if so, he must avoid or minimize contact. However, in determining whether such contact could have been avoided, the circumstances of the check, including whether the opponent put himself in a vulnerable position immediately prior to or simultaneously with the check or whether the check was unavoidable can be considered. This balance must be considered by the Referees when applying this rule. Any unnecessary contact with a player playing the puck on an obvious “icing” or “off-side” play which results in that player hitting or impacting the boards is “boarding” and must be penalized as such."
The penalty can result in a minor, major, or match penalty. A minor penalty happens when the degree of impact is minimal, while a major is for more violent examples that may have ended in injury. A match penalty is when a player deliberately attempts to injure their opponent.
An example of this penalty happened in the 2021 Stanley Cup Playoffs when Joel Armia received a boarding penalty for his aggressive hit on Brayden McNabb. The referees ruled that it was worth a minor penalty, but there was an argument that it could have been more severe.