In the past year I've read a number of different accounts of police using these harmful devices for raids. It boggles the mind that something so dangerous is availble to US police forces as well as being frequently mis-used.
The U.S. Court of Appeals for the 7th Circuit wrote in 2000 that “police cannot automatically throw bombs into drug dealers’ houses, even if the bomb goes by the euphemism ‘flash-bang device.’” In practice, however, there are few checks on officers who want to use them. Once a police department registers its inventory with the Bureau of Alcohol, Tobacco, Firearms and Explosives, it is accountable only to itself for how it uses the stockpile. ProPublica’s review of flashbang injuries found no criminal convictions against police officers who injured citizens with the devices.
Perhaps the most horrifying case of harm by these explosive devices though was the case of Bou Bou Phonesavanh.
Bou Bou was sleeping in a portable playpen at the foot of his parents’ bed when the Habersham County Special Response Team broke down the door to the room and threw a flashbang. The grenade landed on a pillow next to Bou Bou’s face. The blast blew a hole in his chest, severed his nose, and tore apart his lips and mouth.
— Hotter Than Lava by ProPublica
Perhaps the biggest problem though is the attitude that a militarized police force is necessary and keeps people safe. I don't see a problem with police officers carrying firearms in the US, they have done for years, but there is a problem with how much equipment is at their disposal and the lack of constraints in which they are allowed to use it.
Weapons like this belong in the hands of specialist armed forces only, not law enforcers.