Aston Villa manager Paul Lambert is concerned that a "monster" could be created if West Ham succeed in getting Andy Carroll's red card overturned.
Carroll is banned for three games, including Saturday's trip to Villa.
"If it is overruled, then you create a monster of everybody wanting to do the same," said Lambert.
Carroll, 25, was sent off after clashing with Swans defender Chico Flores during West ham's 2-0 victory at Upton Park.
According to the FA, West Ham failed to prove to a three-man panel that referee Howard Webb had made "an obvious error" in dismissing the forward, whose arm hit Flores on the top of his head as he tried to untangle himself following an aerial challenge.
Flores went to ground clutching his face but West Ham felt he had overacted. Replays also showed contact looked unintentional.
West Ham co-chairman David Gold said he was only pursuing legal action because his side, who lie third from bottom in the Premier League table, are involved in a relegation battle.
Former FA compliance officer Graham Bean told BBC Radio 5 live that West Ham should be commended for their stance and are right to appeal.
He said the FA made itself look "foolish" with some of its decisions.
"I think that West Ham, in this particular case, are right to challenge the FA," he added.
Bean acknowledged that the Hammers may "open a vipers' nest" should they succeed in their appeal and force the FA to rehash its rules.
When asked whether he would go down a similar route were his side to be in a similar situation, Lambert replied: "It's hard to say. You can understand West Ham trying.
"You'd have to judge the incident on its merit. Everybody is going to be different, whether they think something is dangerous or not."
The FA is refusing to comment, but the rules allow for clubs to take disputes to arbitration and, if necessary, the Court of Arbitration for Sport.
It is not clear whether England international Carroll's ban would be put on hold until the case has been dealt with.