Does ANYONE understand them? Depressingly it seems not.
If you're joining us late, many years ago there existed a thing oft bemoaned by fans and pundits alike, called the "professional foul". This was a cynical deliberate foul, typically committed by a lumbering centre-half when he'd been skinned by a forward who was then heading clean through on the goalkeeper, but still a long way from goal. The centre-half would blatantly haul him down, making no pretence at a legal attempt to win the ball, and give away a harmless free kick perhaps 30 or 40 yards out.
The forward would thus be denied a chance to go one-on-one with the keeper and very likely score. The defender, meanwhile, would suffer only a yellow card at most – because his foul was in itself usually innocuous (being a simple trip or shove), leaving the referee no grounds on which to issue a red. It was clearly unfair, and something had to be done.
So the laws were altered, and the professional foul was deemed a red card offence. If in the referee's opinion a foul had serious repercussions above and beyond what could be reasonably and proportionately redressed by a free kick – such as the example above – the defender could be directly dismissed.
Another form of professional foul was the deliberate handball on the line. Here, a striker's shot would have beaten the goalkeeper and be about to go into the net, when a defender would deliberately block it with his hand. This would result in a penalty kick, but since the goalkeeper has at least a reasonable chance of saving a penalty, from the defending team's perspective this is better than the absolute certainty of a goal. Again, since the foul in itself was merely a handball – meriting a yellow card at most – the defending team would also be able to remain at full strength, while potentially having obtained the massive advantage of saving a certain goal.
So the "professional foul" rule was written to also encompass, in some circumstances, even fouls which resulted in a penalty. The key to the rule is proportionality – if the normal sanction for the foul is held to be in itself inadequate, ie if even when awarded it still leaves the wronged team at a disadvantage, then the extra punishment in the form of a red card is applied, the purpose being to act as a deterrent. If the normal sanction is an adequate punishment, then no additional one is required.
This, plainly, was the case in today's Carling Cup final. When Nemanja Vidic pulled down Gabriel Agbonlahor, he was about to have a reasonably good chance of scoring a goal. He was through, but with no support, at quite a tight angle, with a defender goalside and trying to harry him, another defender rushing in if Vidic managed to even hold him up for a second or two, and with a goalkeeper about to narrow the angle much more. He might well have scored, but it's very much also within the bounds of possibility that he wouldn't. It wasn't by any means at all, in the wording of the Laws Of The Game, OBVIOUS that a goal was going to result from the chance.
The key is that the sanction for Vidic's offence – the award of a penalty kick – provided Aston Villa with a better chance of scoring a goal than the one the foul prevented. A free uncontested shot from 12 yards in the centre of the box with a goalkeeper forbidden to move forwards is clearly a superior chance to the one Agbonlahor had. Therefore, Manchester United are quite rightly held to have already been adequately punished. The foul has placed them at a DISadvantage, by giving Villa an even better opportunity than they would otherwise have had, which is as it should be.
It follows, therefore, that a professional foul has not been committed, because a professional foul requires that the defending team gain an advantage from the offence even after the stipulated punishment has been issued. So beyond that, the only reason provided by the Laws (specifically Law 12, which lists all the possible grounds for a caution) to take any further action against Vidic is if the player has committed several in succession.
With just three minutes played, the latter clearly wasn't the case – if I remember rightly it was Vidic's first offence of the game – and the foul itself was a run-of-the-mill shirt-pull/missed tackle. Had it happened elsewhere on the pitch at that point in the game, commentators would have bemoaned an over-officious referee for being card-happy and attention-seeking and likely to ruin the game as a spectacle had he issued a caution. That it happened inside the box only increased the cost to Manchester United of the foul by awarding Aston Villa a penalty, so adding yet more punishment by also giving Vidic a card would have been quite unjustified.
The slightly ambiguous way the relevant part of Law 12 is written ("denying an obvious goal-scoring opportunity") with regard to a sending-off offence allows for the sort of idiotic interpretation indulged in by every single commentator and pundit on the TV this afternoon. But the spirit of the law is incredibly clear – it's designed to act as a deterrent to defenders in situations where a foul would otherwise result in an inadequate punishment.
Replacing a difficult goal-scoring opportunity with a considerably easier one is – stupendously obviously – a more than adequate punishment. The referee was right not to issue a card to Vidic. Anyone who says otherwise is a clueless cretin, and that's that.