For those who don't know, they are referring to the 2001 Armando Diaz school attack [1] (warning: graphic), where hundreds of G8 pacific protesters were brutalized and tortured by Italian police. Whilst the police has been found guilty of this, none of the policemen is serving any jail time.
[1]: https://en.wikipedia.org/wiki/2001_Raid_on_Armando_Diaz