TORONTO - Blindside hits to the head will no longer be tolerated in the NHL.

League disciplinarian Colin Campbell has been given the power to hand out supplemental discipline for hits on unsuspecting players where the primary point of contact is the head.

It was officially handed to him Thursday when the executive board of the NHL Players' Association announced that it supported the endorsement of the five player representatives on the competition committee. The league's board of governors had already granted its unanimous support.

The rule took effect immediately.

"We believe this is the right thing to do for the game and for the safety of our players," NHL commissioner Gary Bettman said in a statement. "The elimination of these types of hits should significantly reduce the number of injuries, including concussions, without adversely affecting the level of physicality in the game."

One of the reasons Campbell chose not to suspend Pittsburgh's Matt Cooke after he knocked Boston's Marc Savard unconscious on March 7 was that he felt there was nothing in the rulebook specifically outlawing a shoulder to the head.

A hit like that won't go unpunished now. The NHL's 30 teams have all been sent a DVD that shows specific examples of the type of bodychecks the league wants to see eliminated.

There shouldn't be much pushback from the players given the number of them who spoke out in favour of more punishment while the NHL attempted to fast-track the rule.

"Anything that we can do to make this game safer is a key thing," veteran Anaheim Ducks forward Teemu Selanne said Tuesday night. "If you make big hits and you get a two-game suspension, I don't think anybody learns from that. If you give right away 10 games, then you set the example. It's going to cost you -- big time. I think you're going to think about it twice."

There are only 135 total games left in the NHL's regular season heading into Thursday's play -- roughly 10 per cent of the overall schedule -- but Campbell will also have the power to hand out suspensions during the playoffs.

NHL general managers proposed an on-ice penalty at the conclusion of their annual meetings two weeks ago. That's expected to be discussed over the summer by the competition committee with an eye on instituting it for next season.

The announcement of the temporary modified rule brought a peaceful end to a disagreement between the league and players' union over how rules should be instituted. The NHLPA said it hopes to keep working with the league to make the game safer in the future.

"We are encouraged by the league's recent willingness to explore on-ice rule changes as a means of reducing player injuries and have no doubt that by working together, a safer working environment can be established for all NHLPA members," the union said in a release.