Just this week, we learned two officers will avoid federal charges in the 2016 death of Alton Sterling, a man pinned to the ground before he was shot.
Another officer has been fired for killing Jordan Edwards, a 15-year-old honor student. And yet another officer pleaded guilty after shooting Walter Scott as the 50-year-old was running away.
Date of death: April 29, 2017
Where: Balch Springs, Texas
What happened: Officers responded to a house party after reports of underage drinking. Police spotted a car leaving with five people inside -- including Jordan in the front passenger seat.
At first, Police Chief Jonathan Haber said the car was moving "aggressively" toward officers, and officer Roy Oliver fired into the car with a rifle.
But on Monday, Haber corrected himself and said body camera footage showed the car was driving forward -- away from the officers.
The outcomes: Haber fired the officer Tuesday, saying Oliver "violated several departmental policies."
Date of death: July 5, 2016
Where: Baton Rouge, Louisiana
What happened: Sterling was selling CDs outside a convenience store when police received a call of a man with a gun. Cellphone video showed police tackling Sterling and pinning him to the ground before Sterling was shot. But police said Sterling was reaching for a gun.
But Sterling's death has already yielded change. Baton Rouge Mayor Sharon Weston Broome said $2 million will be spent securing body cameras for the entire police force. On top of that, the city's police training manual will be revised, and officers will receive training in implicit bias, the mayor said.
Date of death: April 4, 2015
Where: North Charleston, South Carolina
As Scott ran away from the officer, a witness captured video of Slager shooting Scott several times in the back.
In exchange for his guilty plea for one of the federal counts -- punishable by up to life in prison -- two other federal charges and state charges were dropped.
Scott's death also led to a statewide change: The South Carolina Legislature passed a bill mandating the use of police body cameras.
Date of death: February 26, 2012
Where: Sanford, Florida
What happened: Martin was walking from a convenience store back to the home of his father's fiance. Neighborhood watch volunteer George Zimmerman spotted him from his car and called 911, reporting "a real suspicious guy."
A scuffle broke out, but there were no direct witnesses. Zimmerman claimed Martin attacked him, hitting him in the nose and knocking him onto the pavement. Zimmerman said he then took out his gun and shot Martin in self defense.
But critics said Zimmerman was unjustified in confronting the unarmed teen, especially since Zimmerman didn't heed a police dispatcher's advice to stop following him.
Date of death: July 17, 2014
Where: New York City
The New York Police Department prohibits the use of chokeholds.
Garner, who had asthma, repeatedly said, "I can't breathe! I can't breathe!" while several officers restrained him on the ground. Police said he suffered a heart attack and died en route to a hospital.
The outcomes: A grand jury declined to indict Pantaleo, sparking protests and "die-ins."
Garner's death also spurred a new protest slogan: "I can't breathe," referring to some of his final words before he died. Several professional athletes wore shirts saying "I can't breathe" in silent protest.
Date of death: August 9, 2014
Where: Ferguson, Missouri
What happened: Brown was walking with a friend in the middle of a street when Ferguson Police Officer Darren Wilson approached them and told them to walk on the sidewalk.
After that, the narratives split. Authorities said Brown had attacked the officer in his car and tried to take his gun. Others said the teenager was surrendering, his hands in the air to show he was unarmed, when the officer opened fire.
Documents showed that Wilson fired his gun 12 times.
The outcomes: A grand jury decided not to indict Wilson -- leading to heated and sometimes violent protests in Ferguson and across the country.
The Justice Department found that "many officers" apparently viewed some of the city's black residents "less as constituents to be protected than as potential offenders and sources of revenue."
Date of death: April 19, 2015, seven days after he was injured
Where: Baltimore
Officers handcuffed Gray and put him in a police van. At some point, Gray suffered a fatal spinal cord injury. He died seven days later.
The outcomes: Six Baltimore police officers, including three black and three white officers, were charged in connection with Gray's death.
The settlement did not "represent any judgment" on whether the officers were guilty or innocent, Mayor Stephanie Rawlings-Blake said.
"This settlement represents an opportunity to bring closure to the Gray family, the community and the city."
Read more here:
'Black Lives Matter' cases: When controversial killings lead to change - CNN