In Genoa last Sunday, a Serie A match was halted for 40 minutes for a demonstration. In democratic societies, peaceful demonstrations sometimes interrupt the normal passage of daily business. They are allowed to. It is a privilege of democracy.
But what happened at the Luigi Ferraris stadium was something distinct. The Genoa "ultras" who climbed into the family section to protest carried an implicit threat of violence. Their anger was against a team who had not won since early February and were 4-0 down at home to Siena, slipping closer to the relegation zone.
Once 60-odd ultras had clambered into menacing positions, including on top of the players' tunnel, the referee halted the match and ushered the players through that tunnel.
The Siena footballers obeyed. The Genoa players remained in an uneasy dialogue with the protesters, who demanded each player's jersey, on the principle they were not worthy of wearing it.
Marco Rossi, the captain, delivered all the jerseys, stripped off by the frightened players, except that of Giuseppe Sculli, who confronted one fan to explain he would not be giving his jersey up. It looked a foolhardy move but Sculli had taken a stand and earned some respect for that.
The match eventually resumed. No arrests were made, although police will study video footage and try to identify ring-leaders. The incident reminded once again that Italy's ultras believe in the power of violent threat. Until all clubs challenge that idea, Italian football will be vulnerable.