Rugby referees from the Northern and Southern Hemispheres have had differing interpretations of the laws of rugby union for more than a decade now.
The principal areas of difference have been to do with scrums—naturally—and at the breakdown, and it is not uncommon for Test matches to rest on whether the referee is from the North or the South.
Indeed, teams will tailor their approach specifically with the referee in mind.
Southern Hemisphere referees have diluted the value of the scrum over the last decade while their counterparts, quite rightly, have respected the traditional front-row battle that makes union so unique.
All the while the IRB has fudged the issue, until recently that is with the new engagement regulations.
Here we look at various areas of the game where refs from both hemisphere can get their collective heads together and finally officiate the game in the same way across the world.
It is fair to say that the pressure to devalue the importance of scrummaging has come from the Southern Hemisphere.
Thankfully their northern rugby cousins think differently and the front rows that gain an edge in this vital and skilled area of the game are rewarded.
Northern Hemisphere referees know their scrummaging much better than those in the south. Why it is this case is anyone's guess because South Africa and Argentina have always embraced the scrum, while the All Blacks are hardly lightweights in this area.
One only has to look at the third Test between the British and Irish Lions and Australia for a prime example of this.
Adam Jones and company had been crushing the Wallabies' front row throughout the series, but only in the deciding Test, when Frenchman Romain Poite was blowing the whistle, were they able to realize their advantage.
The 2003 World Cup final was almost settled by such difference in opinion when South African Andre Watson came close to handing the Wallabies the title when he awarded free kick after free kick to their clearly inferior front row.
The breakdown will always be a contentious area of game. How can it not be when so many players are piling in at the same time and when the rules themselves are so darn complicated.
It would take a referee of international calibre to explain all the dos and don'ts of the breakdown, what the tackler can and cannot do, and when players have come in through the gate or from the side.
But it needs to be consistent. It's never going to be perfect but it needs more clarity.
Ireland legend Brian O'Driscoll is rightly renowned for his ferocious work at the breakdown and his ability to secure the ball after making a tackle. He is a forager of the highest order.
But in the first Test of the Lions series, O'Driscoll was hammered by Kiwi official Chris Pollock. Irish fans, and those from England, Wales and Scotland, were in uproar.
Irrespective of whether Pollock was right or wrong, such a difference of interpretation should not happen at the highest level.
Now that the IRB have finally tried to bring some order to the issue of scrums collapsing and the constant need to reset, referees must follow their guidelines—that means in both the north and south.
The rules state that the scrum-half must put the ball in straight to give both hookers a chance to hook the ball. The days of No. 9's blatantly feeding the ball into the second rows must never be allowed to return.
Already refs have been trying to apply this rule, but they must be vigilant. There is a fair amount for refs to keep an eye on during a scrum, and scrum-halves are still looking to feed when they think they can get away with it.
While there have been some reports suggesting the new engagement regulations have been a success, the experience of others has not been quite so favourable.
Scrum specialists in England, for example, have welcomed the changes and given it their endorsement after several weeks in the Premiership.
England scrum coach Graham Rowntree is very much in favour of it, who told ESPN:
I know why they made the changes to the scrum that they did because as a forwards coach I was disappointed during the Six Nations with the amount of collapsed scrums and reset scrums.
What it will do is enable a pack that wants to scrum to be able to scrum because now if you want to collapse on engagement it is very obvious to the referee who is doing it. I'm disappointed it got to this stage but I but from what I am seeing around the world it is working and there is more playable possession - but it is going to need a bit of time to bed down.
Feedback from the National Provisional Championship in New Zealand suggests it has not improved the need for resets and that the new regulations need further review.
What is needed is patience and an acceptance that these regulations were put in place to lessen the risk from injury with the hit—and hopefully to restore the scrum to its previous position.
Romain Poite got it wrong last week when he yellow-carded Bismarck du Plessis for a perfectly legal tackle on Dan Carter—a cracking tackle in fact that has resulted in the All Blacks' No. 10 needing to spend several weeks on the sidelines.
Refs will always make mistakes but they have been told to be on the lookout for shoulder charges.
These bone-crushing collisions became somewhat of a trademark in certain parts of the world, and while they make for spectacular viewing, they also carry a big risk of injury, especially nowadays with players more powerful than ever.
Coaches, players and referees must buy in to the idea of ridding the game of these kamikaze challenges—which, to be honest, really belong in the NFL—otherwise the lines between what is hard but fair and what is illegal will become even more blurred.
There are times in a game when the team in possession keeps the ball for endless phases due to the fact their forwards are allowed to go to ground and prevent the opposition from competing for the ball.
Munster and Ireland have become experts at this as their players protect the ball with their bodies when they are very often not supporting their own weight.
There is nothing wrong with forwards picking and driving effectively—in fact, it's a great sight—but referees must make players stay on their feet.
Otherwise it can become too one-sided for the team in possession and take out the competition for the ball that rucks are supposed to allow.