On occasion , police and security services have infiltrated black blocs , for purposes of investigation . Allegations first surfaced after several demonstrations . At the 2001 G8 summit in Genoa , among the many complaints about the police there was mention of video footage which " suggests that men in black were seen getting out of police vans near protest marches . " In August 2007 , Quebec police admitted that " their officers disguised themselves as demonstrators " in Montebello . However , the officers purportedly did not engage in violence , and claimed that they were carrying rocks because other protesters were doing so . They were identified by genuine protesters because of their police-issue footwear . According to veteran activist Harsha Walia , it was other participants in the black bloc who identified and exposed the undercover police
G8 summit in Genoa
27th G8 summit
Black bloc