Moving line. Certain kinds of cases (e.g., Henning) will always be decided for the defendant. Or the plaintiffs (e.g., Garner: unarmed nonviolent felon). And then there are the ones where the case must go to the jury. We want to push the case into the Defendant's-judgment-as-a-matter-of-law territory. The lines separating those categories are somewhat movable.
Baton training-- there are many kinds of batons.
Accreditation: voluntary compliance with certain standards.
Sources of knowledge about how to do the job: official policy, by watching and emulating, etc. There are various sources.
"Doing the chicken:" carotid chokehold to render a person unconscious so they can be cuffed, etc.
It's recorded when officers get new policies: they are informed, trained, etc.
There are various types of chokeholds. Many are disfavored, although other versions (i.e., lateral vascular neck restraint) are allowed.
This was unreasonable force, in his opinion. Deadly force. It might have been authorized (i.e., justified under the circumstances), but even if so, there are better ways to deliver deadly force than what was on the tape.
It's very difficult for administrators (or other investigators) to find out about informal practices. It's also hard to find out if they're widespread.
Hard to tell sometimes between a seizure and someone resisting arrest. Officers get some medical training, but often it is minimal. Policies for application of neck restraints can't depend on medical knowledge. There are guidelines, but there's a lot of judgment involved.
Usually other officers monitor the restraint that is applied. In a way, that happened here-- the other officers were trying to save Long from doing something improper, and also save Raheem.
If they had the ability to pick him up, they had the ability to take him to the ground. That might not have neutralized the situation entirely, but that would be a standard approach.
Once Jackson is off of Sal, he's no longer deadly. Maybe they could have justified killing him right when they arrived, but after he was off of Sal, there was no longer a justification for deadly force. The question of when the immanent threat of deadly harm dissipates is a fuzzy one, and those involved in the situation are often too hyped up to recognize it quickly.
Here, though, all the factors for non-deadly resolution were in place.
Tunnel vision is a psychological factor in use-of-force situations.
Properly applied, chokeholds are non-deadly.
Note that the officers don't have non-lethal weapons at their disposal. Maybe they were under-equipped?
Note that other officers know better: they are trying to tell Long to stop. Maybe there wasn't a training problem after all.