It's Rule 48 in the NHL's official rulebook for the 2010-11 season and highlighted in yellow so as to make no mistake about its implementation and importance.

Illegal checks to the head, defined as "a lateral or blind side hit to an opponent where the head is targeted and/or the principle point of contact is not permitted," will now be subject to a five-minute major penalty and automatic game misconduct, as well as possible supplemental discipline if deemed appropriate by the League.

In a conference call Tuesday that included NHL Commissioner Gary Bettman in New York, Senior Executive Vice President of Hockey Operations Colin Campbell in Toronto and Senior Vice President and Director of Officiating Terry Gregson in Prague, the point was driven home repeatedly that as the game has evolved and players have become bigger and stronger, the need arose to better protect them from injuries caused as a result of hits to the head.

"We wanted to preserve hitting," said Campbell, who estimated there were over 50,000 registered hits in the NHL last season. "Our managers felt at this point in time we needed to shift some responsibility from the player getting hit to the player delivering the hit.

"One of the aspects that drove our managers to make this decision, something like 50 percent of our concussions came from hits that were delivered from the side -- call it the blind side for lack of a better term. Our managers felt that by getting rid of this particular hit, it would certainly reduce concussions in the game."

While the aim is to prevent severe injuries, like the concussions suffered last season by players such as Florida's David Booth and Boston's Marc Savard, hockey remains a contact sport and Gregson made clear that just because there is contact to the head, it doesn't automatically make for an illegal hit.

"I think if we look at the video that was sent out, it did talk to the fact there are still legal checks that can occur where there is contact with the head," Gregson said. "The key factor, when I spoke to officials at training camp, the first criteria met is the hit must be coming from the blind side."

Illustrating his point, Gregson referred to a check on Toronto's Phil Kessel which he termed a "north-south hit," in which contact to the head was made but the check was legal because Kessel had the opportunity to see the play unfolding. He asserted that while the new rule "shifts some responsibility to the hitter," it's still the responsibility of the player with the puck to keep his head up and that shoulder-to-shoulder hits from the blind side remain legal plays.

Bettman called the new rule "a fundamental shift" that calls for more accountability on the part of the players without changing the inherent nature of the sport.

"The issue isn't what we didn't do, it's looking at the fundamental and dramatic change we did do," he said. "As with any big rule change, we have to see how it's going to play out. I believe, and I know our managers believe, this was absolutely the right step, and anything broader would have been an over-reaction."

Booth was flattened by Philadelphia captain Mike Richards in a game Oct. 24. He had to be taken off the ice on a stretcher and didn't play again until Jan. 31. Campbell agreed with a reporter who asked if that hit amounted to "the last straw" in the League deciding blind-side hits needed to be addressed in the rulebook.

"The managers had a meeting in November, like we do every year, and this had occurred just prior to that meeting," Campbell said. "They just said, enough, we have to do something about these concussions. Certainly that got us going. We were going to do something about it. We don't do something midseason; never have until the Savard hit took place. We drafted a rule that would apply to supplementary discipline and applied the major penalty this summer."

The Savard play came March 7, when Pittsburgh's Matt Cooke hit the Bruins' center in the head and left him with a concussion. Savard returned briefly during the playoffs, but has not been on the ice since due to linger post-concussion symptoms.

In instances where a player is ejected from a game for a blind-side hit, it will be Campbell's responsibility to determine if any sort of suspension is merited. Bettman threw his support behind Campbell when it comes to making such judgments.

"I think Colie does an extraordinarily good job in understanding what takes place on the ice. I think when he gets done evaluating all the factors that go into supplementary discipline, he is absolutely consistent," Bettman said. "There are nuance differences between acts that some people think are similar, but they're not the same. So you can't be too willing or too quick to paint what happens on the ice that requires supplemental discipline with too broad a brush."