Riot police walk past burning garbage containers during heavy clashes with demonstrators during a 24-hour strike on March 29, 2012 in Barcelona, Spain. Spanish workers staged a general strike to protest the government's latest labour reforms, which are designed to help Spain lower its deficit within EU limits. (Photo by David Ramos/Getty Images)

A member of the punk group p*ssy Riot is restrained by a member of the Cossack militia in Sochi, Russia, on Wednesday, February 19, 2014. Cossack militia attacked the p*ssy Riot punk group with horsewhips on Wednesday as the group tried to perform under a sign advertising the Sochi Olympics. The group had gathered to perform in a downtown Sochi restaurant, about 30km (21miles) from where the Winter Olympics are being held.They left the restaurant wearing bright dresses and ski masks and had only been performing for a few seconds when they were set upon by Cossacks. (Photo by Morry Gash/AP Photo)

Flowers are left at the scene of a hit and run following civil disturbances in the Winson Green area on August 11, 2011 in Birmingham, England. Police are continuing investigations after three people – reportedly trying to protect shops from rioting and looting in Dudley Road – were struck by a car. Police have so far arrested over 1,000 people following rioting which erupted over a four-day period across the UK. (Photo by Jeff J Mitchell/Getty Images)

“Belarus riot police detained scores of demonstrators at a protest rally against President Alexander Lukashenko. Rallies against Lukashenko's rule are rare in the tightly-policed ex-Soviet republic, but protest calls on social networking sites have multiplied in recent weeks as a severe currency crisis has brought economic hardship. Demonstrators gathered peacefully, simply applauding in a coordinated act of protest”. – Af.Reuters.com (Photo by Anton Motolko; Belarus, Minsk; June 22, 2011)

Protesters run for cover after riot police fired tear gas towards the bridge they were climbing down to the road below, to escape from Hong Kong Polytechnic University campus and from police, in Hung Hom district in Hong Kong on November 18, 2019. Dozens of Hong Kong protesters escaped a besieged university campus on November 18 by lowering themselves on a rope from a footbridge to a highway, AFP video showed. Once on the road they were seen being picked up by waiting motorcyclists. (Photo by Anthony Wallace/AFP Photo)

Riot police detain a woman during a protest near Mong Kok police station in Hong Kong, China on September 7, 2019. (Photo by Tyrone Siu/Reuters)