Serbian police officers of the Special Anti-Terrorist Unit pose for a picture in their base outside Belgrade October 8, 2014. When the killing of an unarmed black teenager by a white policeman in Ferguson, Missouri, in August sparked sometimes violent protests, the response of police in camouflage gear and armoured vehicles wielding stun grenades and assault rifles seemed more like a combat operation than a public order measure. Some U.S. police departments have recently acquired U.S. military-surplus hardware from wars abroad, but there are many law enforcers around the world whose rules of engagement also allow the use of lethal force with relatively few restrictions. But for every regulation that gives police wide scope to use firearms, there is another code that sharply limits their use. In Serbia, police may use measures ranging from batons to special vehicles, water cannon and tear gas on groups of people who have gathered illegally and are behaving in a way that is violent or could cause violence, but they may use firearms only when life is endangered. (Photo by Marko Djurica/Reuters)

A Gnawa traditional group performs in the city of Essaouira on December 14, 2019, to celebrate the decision of adding the Gnawa culture to UNESCO's list of Intangible Cultural Heritage of Humanity. Gnawa culture, a centuries-old Moroccan practice rooted in music, African rituals and Sufi traditions, was added to UNESCO's list of Intangible Cultural Heritage of Humanity earlier in the week. Gnawa refers to a “set of musical productions, fraternal practices and therapeutic rituals where the secular mixes with the sacred”, according to the nomination submitted by Morocco. Often dressed in colourful outfits, Gnawa musicians play the guenbri, a type of lute with three strings, accompanied by steel castanets called krakebs. (Photo by Fadel Senna/AFP Photo)

Hollydell Poseidon ridden by Madeline Reader-Smith takes part in the Shetland Pony Grand National Flat Race in Aid of Bob Champion Cancer Trust during day two of the Cambridgeshire Meeting at Newmarket Racecourse on Friday, September 28, 2018. (Photo by Mike Egerton/PA Wire)

In this Thursday, May 25, 2017 photo, Donte, a musician who only gave his first name, straightens out dollar bills on his first day in a brand new Chewbacca costume purchased from eBay for $441, in the Hollywood section of Los Angeles. Donte said he replaced the old one because he wasn't making any money with it. (Photo by Jae C. Hong/AP Photo)

Pope Francis attends a circus performance during his weekly general audience at Paul VI hall on December 22, 2016 at the Vatican. (Photo by Alberto Pizzoli/AFP Photo)

Racegoers have their temperatures checked as they make their way into the course as a pilot scheme for the return of crowds to sporting events is expected to bring in 2500 spectators during day one of the William Hill St Leger Festival at Doncaster Racecourse, England on September 9, 2020. (Photo by BackGrid/The Sun)

A Russian peacekeeper shouts “No pictures!” at a checkpoint outside the city of Stepanakert on November 13, 2020, during a ceasefire in the military conflict between Armenia and Azerbaijan over the breakaway region of Nagorno-Karabakh. Russian began deploying 2,000 peacekeepers to Nagorno-Karabakh on November 10 after Armenia and Azerbaijan agreed a peace deal to end weeks of fierce fighting over the disputed region. (Photo by Alexander Nemenov/AFP Photo)

English model Kate Moss, left, and her daughter Lila Grace Moss wear creations for Fendi's Spring-Summer 2021 Haute Couture fashion collection presented Wednesday, January 27, 2021 in Paris, France. (Photo by Francois Mori/AP Photo)