NFL chiefs on Wednesday vowed to press ahead with the league's new helmet rule despite a storm of controversy which has erupted during its use in pre-season games.
A statement from Troy Vincent, the National Football League's executive vice president, ruled out any possibility of changing the new laws ahead of the regular season.
Vincent said the decision to stick with the rule change was taken after a meeting of the NFL's competition committee.
"The committee resolved that there will be no changes to the rule as approved by clubs this spring, which includes no additional use of instant replay," Vincent said.
"The committee also determined that inadvertent or incidental contact with the helmet and/or facemask is not a foul.
"As all adjust to the new rule, we will continue to provide video feedback and examples of fouls and incorrect calls to coaches, players and officials over the next two weeks and throughout the season as this new rule is implemented."
The NFL toughened up its rules concerning tackles involving the helmet in March in a move aimed at reducing the number and severity of concussions and other head injuries.
As of this season, players who lower their heads to initiate contact with the helmet will face a 15-yard penalty and possible ejection.
However the rule change has drawn a mixed response since being introduced in pre-season games this month, leaving coaches, players and fans confused over what constitutes a foul under the new regulation.
A game between the Minnesota Vikings and Jacksonville Jaguars last Saturday saw a total of 20 penalties awarded throughout the game.
Vikings coach Mike Zimmer later said that the rule change was likely to "cost some people some jobs" during the upcoming season.
"It's just hard to figure out. No one has ever said to me, 'Hey. Don't worry about it, we're going to call it less or we'll get it straightened out in the regular season. Or we're going to come up with a revised rule.' No one has ever said that," Zimmer said.
San Francisco 49ers cornerback Richard Sherman meanwhile slammed the law change as "idiotic" and impossible to enforce.
"There is no 'make adjustment' to the way you tackle," Sherman wrote on Twitter.
"Even in a perfect form tackle the body is led by the head. The rule is idiotic And should be dismissed immediately.
"When you watch rugby players tackle they are still lead by their head. Will be flag football soon."