Let's hear it for referees who jib. Officials who let the game go on, with the same number of players on the pitch as when it kicked off, instead of sticking to the rulebook, spoiling the spectacle, and making themselves the centre of attention.

No? Is that not what everyone wants? There was no doubt who was the refereeing villain of the weekend. The Irish-French rugby union whistler Alain Rolland was roundly condemned for his outrageous decision that lifting a player into the air then turning him over so he falls on his head or neck amounted to dangerous play. But where was the praise, where was the appreciation of Andre Marriner's splendidly laissez-faire performance at Anfield, when he ignored the fact that Rio Ferdinand should have received a second yellow card for his trip on Charlie Adam and kindly allowed Manchester United to remain at full strength against Liverpool so that they could equalise 10 minutes from time?

The two challenges were not remotely similar – one was dangerous though all but unavoidable and the other just the slightest contact yet in a dangerous area of the pitch – but both referees were widely perceived to have done the wrong thing. Rolland should apparently have taken into account that it was a World Cup semi-final he was wrecking – a blithe conclusion absolutely no one would have dared form had the French wing had to leave the field in a neck-brace – while Marriner was accused of cowardice. There were only around 20 minutes left of the Anfield game and so neither the spectacle nor United's cause would have been impossibly damaged by going down to 10 men, but with the score still at 0-0 it would have been a big call to send the visitors' main defender off for two relatively minor fouls.

So Marriner didn't, and luckily for him Steven Gerrard scored from the free-kick, so justice appeared to have been done. The referee got away with that one, his decision seemed just about right in the end, but imagine the fuss had Gerrard's free-kick bounced harmlessly off the wall – as it ought to have done, had Ryan Giggs stood his ground – then United's 11 men had scored a winner through Ferdinand at the other end.

Although personally of the opinion that not every foul on a football pitch need necessarily constitute a booking, one must accept that the equilibrium of that argument is subtly altered when a player has already picked up one yellow card. He has to be extra careful then, and opponents will quite legitimately seek him out and attempt to take advantage of his compromised position. Not by rolling about on the floor, as Adam did, but just by running at the booked defender rather than his team-mates, hoping for either a second foul or an easier way through. That seemed to be what Adam was doing before he overdid the theatrics, and when a player who has already been booked brings down an opponent on the edge of the penalty area to deny a clear sight of goal he really ought to receive his marching orders. Never mind that the two fouls in themselves ought not to have added up to a red card. Had Ferdinand committed his second offence in the Liverpool half or some innocuous part of the pitch he might have been entitled to a degree of leniency, but Adam was running directly at goal and he was stopped illegally just as he was about the enter the penalty area. It was as clear a case of a professional foul as you could witness, even though the contact was not immediately obvious, and Sir Alex Ferguson suggested as much when he said it did not need to be a straight red because Jonny Evans was in the vicinity and Ferdinand was therefore not the last defender.

This was a red herring on two counts. First the concept of "last defender" is not actually enshrined in the laws, which are more concerned with the illegal denial of a clear goalscoring opportunity. Second, no one was arguing Ferdinand should have seen straight red, just a second yellow. He knew exactly what he was doing – actually he did it quite well – and got away with it. Marriner jibbed. That is not quite what this reporter said at the time, because sitting in the stand at Anfield I was unsure of the extent of the contact. It was hard to say whether Adam had dived without provocation or whether he was merely exaggerating his fall to earth so that the referee could not fail to notice he had been clipped. It was still hard to decide even after watching a few slow-motion close-ups on TV, which gives you an indication of how difficult the referee's task was on the pitch, but having judged it a foul Marriner ought to have followed up with a yellow card. Maybe not every foul warrants a booking, but that one did. There seems little point in having the two-yellows-equals-red system if such cynicism is allowed to prevail.

So Marriner got it wrong, while on the same morning on the other side of the world Rolland got it right. He had a hard decision to make, but he made it according to the rules, and quite properly ignored the elevated nature of the occasion and carried out the expressed wishes of the IRB and its refereeing supervisors. Fair enough. But what exactly did Sam Warburton do wrong? His was no cynical or malicious challenge, he was not seeking an unfair advantage or to exploit the rules, he just timed his tackle so well that the French player's feet left the floor. What to do from that point on is not really covered by rugby union's rulebook. Like so many other bits of a code that can often seem irritatingly arbitrary, it is left to the discretion of the referee. Apparently Warburton ought to have put the player down gently, with due attention to his safety, which in the heat of battle seems about as realistic as mentally assessing the size and weight of your opponent in the first place to ensure that he will not be lifted from the ground by your best crash tackle.

What is clear is that rugby union's rules do not properly cover all the eventualities that may take place on the pitch. What is to prevent exactly the same thing occurring in this weekend's World Cup final? Imagine the squawk if that happens, but it is clearly a possibility with powerful athletes in the peak of condition driving into opponents who may happen to be considerably smaller. One almost felt the correct course of action for Rolland to take last Saturday would have been to take into account that no one had been seriously hurt and Warburton's crime was wholly accidental, and restart with a penalty, a warning and perhaps a booking. Yet go down that path and sooner or later someone will get seriously hurt. Rolland did the responsible thing; it is rugby union itself that needs to make some changes to reflect the increased pace, power and sheer physicality of the game.

All that seems a far cry from football, which is rapidly turning into a non-contact sport before our very eyes. Ferdinand complained after the game at Anfield that though he had made contact with Adam, it was not sufficient to make a 12 or 13st player fall over in such a manner. He was right, it was not, but it was possibly the fact that Adam is 12 or 13st that made him look so ungainly falling to the floor. Barcelona players do it much more gracefully, as Sir Bobby Charlton wryly observed after last season's Champions League final at Wembley, and the referee blows for a free-kick every time.

Rugby union is going beyond contact and evolving into a collision sport. Football is going in completely the opposite direction, and Ferdinand, with his recent harrowing experiences against Barcelona, should know that better than most. His was only the tiniest of trips on Adam, so slight a clip that the referee could easily have missed it and many observers wondered why on earth the Liverpool player did not stay on his feet and have a shot at goal. But that is no longer the point. For Ferdinand to admit to a foul and simultaneously demand Adam should stay upright was positively antediluvian. Like it or not, those days are gone.