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)

Enya Kim from the Natural History department at auctioneers Bonhams & Butterfields stands in front of one of the world's largest set of shark jaws comprised of about 180 fossil teeth from the prehistoric species, Carcharocles megalodon, which grew to the size of a school bus, at the Venetian Resort Hotel Casino September 30, 2009 in Las Vegas, Nevada. (Photo by Ethan Miller/Getty Images)

A concept illustration of the world's first forest in the sky, the Bosco Verticale green twin towers currently under construction in Milan, Italy. Towering over the city skyline the world's first forest in the sky will be a sight to behold. With tree equal to one hectare of forest spanning 27 floors these 365 and 260 foot emerald twin towers will be home to an astonishing 730 trees, 5,000 shrubs and 11,000 ground cover plants. (Photo by Boeri Studio)

A painted figure is seen on a wall of the home of the mother of Robert E. Crimo III, the 21-year-old suspect facing seven counts of first-degree murder in an attack on a Fourth of July parade, in Highland Park, Illinois, U.S. July 6, 2022. (Photo by Cheney Orr/Reuters)

A man walks past a mural depicting US actors John Travolta and Samuel L. Jackson holding thermometers instead of guns amid the Covid-19 pandemic, in Tel Aviv on March 1, 2021. (Photo by Emmanuel Dunand/AFP Photo)

Women sells vegetables at Kaporo market in Conakry, Guinea Monday, September 13, 2021. (Photo by Sunday Alamba/AP Photo)

Afghan tea seller Farooq Shah, center, fills kettles with tea for customers at a market place in Kabul, Afghanistan, Wednesday, December 4, 2019. (Photo by Altaf Qadri/AP Photo)

A mural painting by graffiti artist Eme Freethinker features likenesses of US President Donald Trump (R) and Chinese premier Xi Jinping wearing face covers in Berlin on April 28, 2020 amid the new coronavirus COVID-19 pandemic. (Photo by John Macdougall/AFP Photo)