None. You just look at whether when he passes it it comes out of his hands backwards taking no account as to where it ends up.

And if the player is running at any other angle than straight towards the posts? (90% of the time)

The refs look at how the ball came out of the players hands. Not where it goes relative to the ground.

Whilst momentum may not technically be the correct word to be used, the rule is not mythical. The only rule that is mythical regarding forward passes is that the ball has to go backwards, relative to the ground, from the point of release.


If you want to mathematically work it out you need to know the forward speed of the player passing the ball and then see if the ball's forward speed increases or decreases from that speed. (For the mathematicians out there I'm aware im probably not using the correct terms but, mostly for my own sake, I'm trying to keep it simple)

So let's say a player is running forwards at 10 m/s (I know that's too fast but it makes the maths easy for this) and passes the ball directly on the halfway line. If the ball then continues forwards faster than 10 m/s it's a forward pass because it's been given additional force in a forwards direction. If it continues forwards slower than that then it's not a forward pass because it's been given additional force in a backwards direction.
So if it reaches the 40m line (because it's going downfield at 10m per second anyway) in less than a second (faster than the player's speed) it's forward, if it's more than a second (slower than the player's speed) it's not forward.


That's the problem with saying that the rule should be relative to the ground. You make it almost impossible for passing whilst running at speed. Because you have to overcome the forwards momentum of the ball which you don't have from, say, a dummy half pass off the ground.

A quick example:

Player A is stood still on the halfway line and passes the ball directly behind him with enough force to propel the ball at a ground speed of 10m/s. In this case the ball would reach his own 40m (ie behind where the player is stood) line in 1 second.

Player B runs at a speed of 11m/s. (Again I know that's not right but I'm keeping the maths simple) When he reaches the halfway line he passes the ball directly behind him with exactly the same force as player A. Unlike Player A, instead of reaching his own 40m line the ball would actually cross the halfway line and end up 1m further downfield (51m) than where the ball left his hands.

2 players pass the ball in exactly the same fashion, neither should be given as forward passes because they've both been passed backwards.

Almost all refereeing is subjective - knock on? High tackle? Ripping the ball?
You don't allow any tolerance for momentum. As you say, it's a mythical rule.
I'm not familiar with rule changes going back over the last 100 years but I imagine forward passes were judged the same as today ie. according to the rules of the day.
As I said, the rule is simple but applying it isn't. However, change the rule and it would disadvantage skilful, fast play.

The physics behind it is relatively simple, im sure somebody could explain it in a better or more accurate fashion than I can.

The method of determining whether a pass is forward or not is simple. Did the ball come out of the players hands forwards or not?

Now having a referee who is often not in the perfect position, who also has to make literally hundreds of decisions per game, and has to think about lots of other issues at the same time make the decision on forward passes means we will always get some right and some wrong decisions, regardless of the rules. We see passes that are forward not given even though there is no "momentum" (eg from acting half) as well as those that do involve "momentum" (eg a 2-on-1 with the full back).
But that's refereeing mistakes (some understandable, some not) not a problem with the rules.

As I said, if you implement the "forwards relative to the ground" rule, it disincentivises players passing whilst running at anything much above an average prop's pace.

You're all forgetting the Mcquire factor. If Danny's involved does the ref disallow the try and risk him whining in his ear for the rest of the game or just take the easy option and give the try?

See now I always thought it was just a 50/50 choice between McGuire or Maguire. Kudos on the originality there though

Bet you wouldn't have said that if he got you in a headlock

For me this is fairly simple, but it's been made more complicated by Stevo banging on about the 'momentum rule,' which doesn't actually exist; now we have rugby league fans trying to argue about physics, both usually from a position of misunderstanding - it's potty.

The judgement is all about which direction the ball left the hands - which isn't easy to call on when the game is played at breakneck speed and the passing motion is often made amidst a melee of 20 stone RL players who block out the sun.

It could be made easier if players and coaches were made aware that the ball must go backwards from the hands and not just not forwards i.e the dreaded 'line ball' - a strategy that Leeds have employed to bend the laws of space and time for a number of years.

Also - why not look at a) some technology and b) making better use of existing resources - make TLO's more responsible for advising the ref; they're in line with play and should have a better view. I'd also think about using the VR, but that causes issues in terms of slowing the game down and the fact that there isn't a VR at every game.

It's a conundrum - the only real certainty is that Leeds are dirty cheats.

p.s I can confirm that disincentivise is indeed a real word.

GPS technology in the ball?

Perhaps the game could be played out in a virtual grid, Tron style, where every movement of the ball could be mapped electronically and ruled on instantaneously; the players could be suspended in a large harness where their every motion is translated to that of their electronic avatar, a bit like them big robots off of the opening credits of the Sky coverage. There would be no need for a ref, a stadium, a crowd or Eddie Hemmings, and cheating would be literally impossible. Craig Charles could present it, with Sir Killalot doing analysis of the accuracy of the algorithms; Robot Superleague - the kids would love it.

I think that would only tell the direction of travel of the ball relative to the ground and we would have exactly the same disagreements we have now.
Its impossible for a ref to be in the best position to spot all infringements all the time so perhaps the answer is for TV "experts", fans, coaches and players to stop analysing every decision to the nearest millimetre and for us to accep that refs, sometimes get it wrong ( but then who doesn't?)

It's quite possible to detect a forward pass remotely. As you say some kind of position sensor for the ball would tell you where it was and from that you can work out everything else. If you measure the position again a short time later you know which direction it's gone and also how fast it's got there but that's not really helpful. Once you know the speed you can then work out the speed are short time later which gives you the change in speed or acceleration which is what you need. Any acceleration of the ball in the direction of the opposition's posts at the moment the pass is made would indicate a forward pass. You'd have to sync the data with the video to check a bit like the clip meter for cricket.
Alternatively, we could stop listening to sky's incessant search for controversy at every decision and realise that the human refs actually get it right almost all the time despite what the partisan fans think.