In the recent Man City vs Portsmouth match, Ben Thatcher deliberately elbowed Pedro Mendes in the face. Mendes was knocked unconscious, and suffered a fit on the way to hospital. Thankfully, it doesn’t seem that any lasting damage was done; things could have been a lot worse. Everyone, even Thatcher’s team-mates and manager, agreed that it was a disgraceful challenge.

So far, Thatcher’s punishment has been too soft. The referee, who clearly should have shown him a red card, only booked him. His club have since fined him £22,000, which is substantial but, for a Premiership footballer, easily affordable. The FA is trying to find a way to impose an additional punishment, which would presumably be a ban of about half-a-dozen games, but generally only impose retrospective punishments for match incidents that the referee missed completely, rather than incidents like this one where the referee saw it but got it wrong.

Some have said that in addition to any punishments imposed by Man City, Thatcher should face criminal charges for assault. There is some precedent for this–about a decade ago, Duncan Ferguson was once charged by the police for a head-butt that happened during a match–but generally the attitude of those in the game is that what happens on the pitch stays on the pitch.

Thatcher’s manager Stuart Pearce, and player and pundit Danny Mills have offered similar arguments against police involvement. In comments reported by the BBC, Pearce put it like this:

“Anything that happens on a football pitch should be governed by the FA and FIFA. Once you start involving the police, the floodgates can open and you could end up with a situation where players are arrested during a game.”

The argument here is that if the police get involved in this incident, then they’ll end up involved in every incident, and that would be undesirable. To avoid that situation, we should resist police involvement in this incident. This is a classic example of the slippery slope fallacy. It’s perfectly possible for police to get involved in a very few cases without being drawn into every game.