Images and video ofand bruised bodies have flowed steadily on social media and in the news over the past week as police across the country have at times used violent tactics in response to .
The use of what are known as "less than lethal" devices on such a large scale is unusual, according to experts on policing and criminal justice. Despite the terminology, use of these weapons can sometimes be fatal.
"What we're seeing is escalated force among law enforcement, which entails the use of tear gas, rubber bullets, pepper spray, flash grenades, all of this is highly confrontational and aggressive in nature," said Jennifer Cobbina, a Michigan State University criminal justice professor who specializes in police-community relations. "What it will do is it will increase levels of violence and, which also further exacerbates the problems between protesters and the police."
For her book, "Hands Up, Don't Shoot," Cobbina interviewed nearly 200 residents of Ferguson, Missouri and Baltimore after police cracked down violently against protests in those cities following the deaths of Michael Brown and Freddie Gray. She said police have a history of violence tied to protests against police violence.
"I will say that this is not uncommon to see force used when the protesters are largely comprised of people of color," Cobbina said. "The use of escalated force is rarely used when the protesters are largely comprised of white individuals."
Police are taught a "continuum of force" that emphasizes first relying on low-risk methods and increases to the most dangerous type of crowd control — rubber bullets, according to former Bergen County, New Jersey Chief of Police Brian Higgins.
But Higgins said in the last week high-risk weapons are being used more than he can remember.
"We are at the point where I've seen this ammunition being used more than I've seen it in a long time or, or maybe even in my career," said Higgins, a use-of-force expert who is an adjunct professor at the John Jay College of Criminal Justice in New York City. He said he's seen both questionable and seemingly justifiable examples of force being used by police in the last week.
The "continuum of force"
Higgins described where certain weapons and strategies fall in the "continuum of force," from least lethal to most dangerous, for CBS News.
Being uniformed and present: The lowest level of force on the continuum is the mere act of being visible, armed and uniformed, Higgins said. "It's referred to as constructive force, which is the mere presence of a law enforcement officer at the scene. Just in uniform."
Batons and shields: Around the country, officers have been seen using their shields to either push back crowds, or as weapons to strike people. The use of batons to beat protesters has been widespread. In Washington, D.C. on Monday, police could be seen on live television striking an Australian cameraman with his shield, before grabbing the cameraman's equipment.
Pepper spray: One of the most common tools for dispersing crowds, pepper spray is a concentrate of capsaicin, the chemical that gives peppers their heat. It's considered to be on the lower end of the continuum of force, but a 2016 ACLU report found more than two dozen deaths associated with pepper spray inhalation in just a two year period.
Flash bangs: Also known as stun grenades, these devices combine a bright flash with a high decibel burst of noise. They were reportedly used to clear protesters from Washington's Lafayette Park Monday socould walk through the area on his way to be photographed . Higgins said they're meant for indoor operations when advancing police want to momentarily stun potentially hostile, or armed people, and are not typically used outdoors for crowd control.
Tear gas and "OC" gas canisters: These chemicals are often deployed to disperse crowds, but are not supposed to be used against peaceful protests. Both chemicals cause long-term health risks, according to the CDC.
Pepper balls: These projectiles pop on impact, spraying capsaicin. Higgins said these can be "extremely dangerous." He pointed to the death of Victoria Snelgrove, who in 2004 died after being shot in the eye with a pepper ball as Boston police sought to clear a crowd of revelers following the World Series.
Rubber bullets: Higgins was unequivocal about the dangers of rubber bullets, these projectiles — often coated in rubber or other materials — can be deadly, he said.
"They're referred to as 'less than lethal ammunition.' When they first came on the market, they were referred to as non-lethal. And in very short order, we realized that that's not true," said Higgins, adding that the consequences can be devastating when fired at close range or toward the face. "We know that people die as a result of using these rounds. So it's the highest end before the use of deadly force."
Higgins said officers are trained to shoot rubber bullets at lower extremities, and never indiscriminately toward groups of people.
A 2017 study in the medical journal The BMJ found that since 1990 at least 53 people had died from injuries sustained from rubber bullets, and nearly 1,500 more had sustained severe injuries.
What if police don't use force at all?
Cobbina said some police departments have historically been taught another way to handle protests, a method called negotiated management, which shuns antagonism. This strategy traditionally calls for officers to meet with protesters to discuss protest logistics as well as how and when police would move along the force continuum.
"This is where law enforcement makes a concerted effort not to aggressively engage protesters. They try to avoid mass scale arrest as well as avoid the use of violence," Cobbina said.
She said the most prominent recent images of negotiated management have included displays of solidarity with protesters, such as when law enforcement marches alongside them or kneels with them.
"Some of the evidence shows that this approach is certainly much more effective in trying to avoid exacerbating and causing tense situations, while also allowing for some community disruption" Cobbina said.