Why Kohli and Warner weren't charged
Around the same time that the ICC heard the Faf du Plessis case, there emerged on social media footage of Virat Kohli and David Warner with suggestions that they might have introduced artificial substances to shine the ball.
That footage, though, was not a consideration for the ICC because any Level 1 or 2 offence under the ICC Code of Conduct has to be brought to the notice of the ICC match referee within five days of the incident.
Du Plessis' footage - which has proved him guilty of altering the state of the ball based on the evidence that "showed an artificial substance being transferred to the ball" - was brought to the ICC's notice within five days, following which it reviewed the footage and then decided if it merited investigation. The charge on du Plessis was brought after the investigation. The footage of Kohli and Warner didn't even reach the stage where the ICC would decide if they merited an investigation. The Kohli footage is from the second innings of the Rajkot Test, which began on November 9. Warner's is from day three of the Hobart Test, which began on November 12.
Only the match umpires, CEOs of the two participating boards or the ICC CEO can report an alleged offence under the ICC Code of Conduct. Apart from those made by the ICC CEO, the other reports under Level 1 and 2 - du Plessis' was a Level 2 offence - have to be made within 48 hours of the event. If the ICC CEO makes the report, it has to be done inside five days.
Clause 3.2.2 of the ICC Code of Conduct says:
"Where the Report is lodged by the individual described in Article 3.1.3 [the ICC CEO] in relation to:
188.8.131.52 a Level 1 Offence or a Level 2 Offence that is alleged to have been committed at any time or place (whether on the field of play or otherwise), then the Report must be lodged with the Match Referee (or, where, for logistical reasons, it is impractical to lodge with the Match Referee, the ICC's Cricket Operations Department) within five (5) days of the commission of the alleged offence"
The Level 2 charge on du Plessis was laid by the ICC CEO David Richardson on November 18, three days after the incident. Offences under Level 3 and 4 can be reported within seven days but it is fair to assume Kohli and Warner - if they merited being charged - would not have been charged for a more serious offence than du Plessis'.
Whether the available footage of other players allegedly introducing artificial substances to the ball brings any change to how the ICC deals with ball-tampering depends on either the MCC or the ICC cricket committee. Former players of varied nationalities - Sourav Ganguly, Jason Gillespie and Matt Prior to name a few - have said in the last week that the use of a sweet or a lolly or a mint to shine a ball is a practice widely prevalent in cricket.
"Amongst the players the lines are pretty clear & use of mints/sweets to shine the ball is accepted," Prior responded on Twitter when asked what the line regarding ball-tampering was.
"Not everyone scratches the ball on their zipper but EVERYONE uses sweets! You'd have to fine/ban a player every match," Prior went on to tweet.
The ICC looks at lessons it can learn from every incident so this case should be no different. If it is deemed that a change in laws is necessary, it falls under the realm of the MCC, whose head of cricket John Stephenson was present at the hearing.
The ICC Cricket Committee, likely to meet next at Lord's in May 2017, discusses all cricket-related issues every year. If it feels the playing conditions need to be modified in the light of what former players say, the change is likely to be made in May. Unless it is considered an emergency, in which case they can meet over a tele-conference.