Players chief Gordon Taylor has questioned the Football Association's decision to charge Wayne Rooney for swearing into a TV camera after his hat-trick against West Ham.
The England striker was charged with using abusive language and has until 6pm on Tuesday to indicate whether he will accept the charge - which would carry a two-match ban - or appeal against it. Professional Footballers' Association chief executive Taylor entered the debate by issuing a statement on the PFA website.
It read: "Whilst the use of foul and abusive language is not condoned, there is an acceptance by all parties within the game that 'industrial language' is commonly used. It becomes an issue when directed towards match officials. However, when used in a spontaneous way in celebration or frustration then it is not normally expected to merit a sanction."
The statement continued: "If sanctions are to be imposed in such circumstances then this has to be done in a balanced and consistent manner, and participants made aware of this fundamental change in approach."
If Rooney accepts the FA charge he would miss United's Premier League home clash with Fulham on Saturday and the FA Cup semi-final meeting with Manchester City a week later.
The charge was described on the PFA's website as being "unprecedented" and, if upheld, would set a "dangerous precedent" leading to a greater number of players being dismissed.
PFA deputy chief executive John Bramhall said: "I think it puts them (the FA) in a difficult position if they do set a precedent that using foul and abusive language on the field of play is to be treated in this way.
"Then it could lead to a very serious situation with regards to our members, who in previous seasons have been working with an acceptance level, a tolerance level which clearly has now been changed.
"None of the participants in the game have been involved in the discussions even though there have been on-going discussions between all the stakeholders within the game looking at what is acceptable within the game."