The International Cricket Council's match referee Jeff Crowe fined Australian captain Michael Clarke 20% of his match fee under 2.1.4 of the ICC's Code of Conduct - "Using language or a gesture that is obscene, offensive or insulting during an International Match.". It was a Level 1 charge, the mildest available.
There are a few misunderstandings about how the ICC's Code of Conduct procedure works. Match Referees cannot bring charges, except in very specific and limited circumstances. Charges can be brought by the Umpires, by the team managements or by the CEOs of Cricket Boards. Match Referees cannot do anything unless a charge is formally brought in a given situation. This is why a number of situations which appear to merit a charge in the eyes of cricket fans go unaddressed.
But here, there is an interesting point to be made in light of the Clarke affair. James Anderson complained to the Umpires about Australian sledging. Once that happened, the Umpires are more likely to report it. It is a wonder that players don't use this reporting procedure more often. Now that Clarke has accepted guilt in this one instance, England's players ought to keep an eye on him and complain about him at the slightest provocation, since a second offence will hurt him more than the first one. Under the ICC's rules, this sequence can eventually lead to suspension.
Sledging comes with many strings attached. For it to exist, there has to be a gentlemen's agreement that both sides will not involve the umpires. There has to be an agreement that what is said on the field will be left on the field. There are other guidelines (if you will) about humour and language. Benign explanations liken sledging in international cricket to school yard banter, albeit among highly skilled grown ups.
What Michael Clarke said has been construed as a "physical threat" to Anderson's well being. I disagree with this characterization. After all, the phrase "chin music" is commonly used by cricket fans and players alike. It is even celebrated as a fine art. It is not clear what Clarke's offense was. After all, the great West Indians never said anything, but their unblinking stares would never be confused with "I'm going to square you up and clip the top of off stump". The stares, the very presence of pacemen - be it Michael Holding or Curtly Ambrose or Jeff Thomson or Allan Donald - carried with it a physical threat. The existence of Short Leg as a legitimate fielding position relies on the fact that batsmen will fend deliveries in order to protect themselves from getting hurt. Short Leg doesn't exist to catch firm clips off the pads, whatever Ishant Sharma may think.
The physical threat is a legitimate part of batting. Clarke's crime, if at all, was that he crudely said what every team that has selected a genuine fast bowler deliberately pursues - conveying to batsmen that covering the line and defending stoutly brings with it the risk of physical harm. The physical threat is not legitimate because it makes for great viewing. It is legitimate due to the very definition of the game. Cricket is played with a hard leather ball and its rules are designed keeping this in mind. If the game was played with a hollow ball (like say a heavier version of a tennis ball). If the physical threat was not legitimate in cricket, short pitched bowling would not be legal.
The ICC finds itself in a peculiar place with this. It has been suggested that the real problem in the case of Clarke was the his comments were heard on the broadcast via the stump microphone. Clarke's comments were neither offensive, insulting or obscene. They merely reflected a core aspect of hard ball cricket. But the ICC had to do something for two reasons. First, it looked bad because it was heard on TV. Second, Anderson complained, thereby dragging Australia's behavior outside the gentlemen's agreement. Anderson's complaints could be construed as whining. Given England's position in the match at the time, it could be reasonably construed as a loser's whining. But they could also be construed as legitimate use of a tool - the code of conduct - the ICC has placed in the game.
The Code of Conduct exists to keep player behavior in check. This is a fraught idea, for very few things are universally considered equally egregious, and early efforts by the ICC to check player behavior ended up being biased against sub-continental players. A number of things considered commonplace in Australia, South Africa, New Zealand and to a lesser extent England, were considered offensive in India and vice versa. Matters came to a head when referee Mike Denness charged six Indian players in a single game in South Africa in 2001. The backlash was severe and the ICC's response was to take away the referee's authority to bring a charge and transfer this responsibility to the Umpires. This resulted in the Code being applied piecemeal, because Umpires would only bring charges in matters where they felt they were on the surest ground. Additionally the Code became both more specific and more broad. It covered more ground and defined that ground more unambiguously. This has had fine consequences for some offences such as over-appealing (which in my view has to be policed, and is policed very well). It has had decidedly adverse consequences in other matters relating to the character of players involved.
Due to the many pressures placed on it, the implementation of the Code of Conduct has become both piecemeal and narrow. It exists today as much to protect the ICC's officials as it does to regulate on-field conduct of players. Sledging is one of these areas in which the code has never been satisfactory, mainly because sledging is acceptable or unacceptable depending primarily on how the players see specific acts. The Australians for example, seemed genuinely upset about Andrew Symonds being called a monkey (as they alleged happened), but were up in arms when one of their players was accused of using a similar epithet against Sanath Jayasuriya. England have little to say about one of its players saying he wanted to "kill" an opponent who was a "cheat", but think it is excessive for a opponent to warn one of their batsmen of impending physical harm if he continued to get in line.
Sledging should be allowed if it is verbal. It is much more reasonable to take a benevolent view of sledging than of ball tampering. To police sledging is akin to policing passionate argument. In the dreadful parlance of our time, it amounts to focusing on the tone of an argument while ignoring the substance of it. The substance of a sledge is a dare, a challenge, a claim of superiority. It cannot be more until it also includes an invasion of an opponents personal space, at which point, it cease to merely be a sledge.
If the ICC was less interested in appearances, and more in substance, it would insist that sledging be managed by umpires as they see fit, on the field, and left there.