Using a hand to handle the puck in hockey is usually illegal and results in a penalty or infraction, but the specific result of the play depends on the nature of the hand usage. If the team is in their defensive zone, a hand pass is actually allowed, but in the offensive zone, a stoppage occurs as the result of the play. This infraction happens because hand passing allows for pinpoint accuracy and control of the puck.
Defensively, players are allowed to stop the puck in the air without a penalty or stoppage. The player is not allowed to throw or force the puck in any direction, but there are still ways to handle the puck with the gloves. A player can catch the puck, but they have to drop or place the puck on the ice as soon as the player can.
In rare situations, a hand pass can result in a goal. This situation occurs when a defending player grabs or swats the puck from the goal crease when the goalkeeper is not on the ice. Specifically, the player must have prevented what would have been an obvious goal. This rule stops a team from pulling their goalie and just using their hands to save the puck, as empty net goals generally happen from the blue line, so they are usually sliding across the ice to the net.
The state of reviewing hand passes causes some controversy in the modern NHL. Hand passes that go directly into the net are reviewable and able to be overturned. Hand passes that create a scoring chance rather than a direct goal, though, are not reviewable. This rule is controversial because if the referee misses a hand pass call before the goal is scored, the goal will stand regardless of how egregious the infraction was.
In the 2019 Stanley Cup Playoffs, an obvious hand pass was missed in Game 3 of the Western Conference finals (St. Louis Blues vs. San Jose Sharks). During the play, Sharks player Timo Meier executed a hand pass to Gustav Nyquist who then set up Erik Karlsson for a game-winning goal in overtime. This infraction didn't taint the series, as the Blues won, but it underscored the importance of identifying illegal hand passes.
Hand passing in the defensive zone is allowed in the NHL because the situation is less likely to create a game-changing play in that zone compared to the offensive zone. Hand passing does not immediately clear the puck from the zone, so the team must still make an effort beyond that play to start an attack. When a hand pass happens in the offensive zone, the team immediately benefits and gets a quality scoring chance.