Choked to Death by Police?

Eric Garner was a 40-year-old black man, that was 400 pounds and had breathing problems. On July 21, he was suspected of selling illegal cigarettes on the street. During his arrest, he refused to cooperate with the police, forcing them to take action; they took hi into the chokehold and brought him  to the ground. The entire time he was yelling he couldnt breathe, but the police did not stop, then he suddenly passed away.
In my public saftey class, ive learned that it is illegal to take someone down to the ground when you are a police officer. So, why did they. Police have many alternative methods to make someone cooperate then using violence.
in my opinion, the situation should have never esclated to where garner was on the ground.
What would you have done differently if you were the police officer? Do you believe this is a crime or just accident?
Want to know more? watch the video below.