Referee Cuneyt Cakir sends off Manchester United's Nani (red 17). Pic courtesy of PA.
It is noticeable that many Referees (see here) have sided with Cakir's decision, claiming that it was a send off for serious foul play, while other Referees did not think the incident warranted a red card (see Dermot Gallagher). Also, with the exception of Roy Keane, the majority of players, ex-players and fans thought Cakir's decision was harsh. Here's HKRef's take on the incident:
First Consideration
Cakir sent off Nani for serious foul play, which means a player is dismissed for using "excessive force or brutality against an opponent when challenging for the ball when it is in play". The laws further state: "A tackle that endangers the safety of an opponent must be sanctioned as serious foul play."
The Nani—Arbeloa challenge. Pic courtesy of EPA.
Following these Laws to the letter, it is easy for everyone to understand why Cakir was not wrong to send off Nani. Cakir's view is Nani endangered the safety of his opponent.
Second Consideration
However, only a few days earlier in the English Premier League match between Stoke City and West Ham United on 2 March 2013, Stoke's Peter Crouch launched into a bicycle kick and connected flush with Matt Taylor's face, and knocked him out for a few seconds.
Stoke's Peter Crouch (red/white 25) connects with West Ham's Matt Taylor's jaw. Pics courtesy of PA.
West Ham's Demel (maroon 20) reacts in anger towards Crouch
Referee Jon Moss awarded a free kick to West Ham and was wrong not to caution Crouch.
To many referees this was a reckless challenge. "Reckless" is defined as a player who has "acted with complete disregard to the danger to, or consequences for, his opponent. A player who plays in a reckless manner must be cautioned."
The Laws state: "A scissors or bicycle kick is permissible provided that, in the opinion of the referee, it is not dangerous to an opponent."
Further Considerations
The Crouch—Taylor scenario also technically fits the criteria of serious foul play because the offender endangered the safety of his opponent. But Crouch's action had no malice or any intent to injure. Plus players react to and accept bicycle kicks all the time; we know this because such kicks are used frequently by players.
It is these two definitions — one for a sending-off, the other for a caution — that appear to contradict each other. For bicycle kicks, players intuitively know it is reckless because there is no intent to kick an opponent, only a complete disregard to, since the offender does not look at his opponent before executing the kick.
Q: Did Crouch's bicycle kick endanger the safety of an opponent? If yes, then RC.
Now consider the Nani—Arbeloa challenge; was it reckless or serious foul play? Did Nani intend to kick Arbeloa with his studs exposed and was Nani looking at Arbeloa? Also, the reactions of the players told us that, at most, it was a reckless challenge. Had Cakir cautioned Nani for being reckless, he would not have been wrong.
Q: Did Nani act with complete disregard to the danger to, or consequences for, his opponent? If Yes, then YC.
Conclusion
The problem perhaps lies with the Laws and the way different competition organisers interpret them. The argument that "Nani deserves a red card on the continent and only a caution in England" is ignorant.
We can see from the reaction of Real Madrid's players that in Spain Nani would not have expected to be sent off either. The respective Football Associations in England, Spain, Germany, France and the Netherlands would likely interpret Nani's challenge to be reckless.
But UEFA is the competition organiser of the Champions League. Its referees committee, headed by Pierluigi Collina, manages its interpretation of the Laws and relies on top FIFA match officials from Europe to implement them publicly. Apparently, Collina and his Committee view this type of challenge as serious foul play.
Therefore, Cakir had an incentive to exhibit boldness and send off Nani at Old Trafford because he knew Collina was assessing him, probably with May's Wembley final in mind. Collusion?
A Final Note
Looking at the slow motion replays, did anyone detect Nani apparently straightening his right leg in the split-second after the coming together of both players? In real time, it is hard to detect, but this could be Cakir's proper justification in issuing a straight red (providing, of course, that Cakir saw it in real time).