Re: No Indictment in Chokehold Death
Note that there are two distinctive different styles of "chokes". An air/windpipe choke and a blood/Carotid choke.
The first type focuses on actually impeding the pathway in which the body takes in air by constricting or attempting those pathways. It typically is far more difficult to get a true "Choke out" from a choke like this, and thus is more used as a means of inducing pain and/or the feeling of trouble breathing...perhaps for compliance purposes, or to help force a reaction that opens up a transition to a blood choke. These kind of chokes typically are ones that utilize an instrument or a portion of the body directly across something like the trachea.
The second type focus on impeding pathways that bring blood, and thus oxygen, to the brain, usually by applying pressure to something like the carotid arteries. These kind of chokes are the ones most commonly resulting in a "chokeout" type of effect, sometimes very quickly. Pain on these is generally significantly less than on an air choke, with it being more a feeling of intense pressure. Typically this is better for actually incapaciting someone than necessarily compliance purposes.
The second picture you have there is pretty much textbook blood choke. The bicep and forearm form a V, applying pressure to the carotid as it's primary method of "choking".
The first picture is closer to an air choke, as you can see the forearm is (somewhat) across the throat and there's not a lot of pressure on the carotid. However, there's a couple of caveats here.
1) It's not uncommon to see someone that is attempting a blood style rear naked end up in something akin to the air choke variation for averity of reasons (i.e. poor technique, not fully getting the arm into position, the person attempting to work out of the choke). So it's possible that's in this instance the cop was going for a blood choke, and for whatever reason it ended up an air choke.
2) Either way, he's appears to potentially be doing it poorly (possibly due to technique, possibly due to actions by the person he's attacking, impossible to say). If he's trying for a blood choke, he's failing miserably. If he's trying an air choke, he's may still not be doing a good job of it, though that's a bit harder to see. For an air choke you want the focal point flat against the pathway you're attacking, not at an angle which will apply uneven pressure and make space that can be used to resist. His arms at an angle there, though it's hard to tell if that's because the guys throat is truly turned at that same angle or if it's just him misapplying it.
To Rev's point...in the way it's being talked about here, in terms of a "chokeout" type effect, an air choke could probably be accurately described as more of a "hold". Air Chokes are painful, and make breathing very difficult, but don't normally result in an easy means of unconsiousness. In some ways it's more comparable to a joint lock or pressure point and other form of pain compliance "holds" than a blood choke. To rev's point as well, in many cases with an air choke (especially with someone doing it poorly), there's still air that can be coming through allowing for speech.
Had this been a perfectly healthy person I'm unsure if we would've even seen him truly fall unconsious unless the officer significantly managed to shift his choke around. However, given that the individual had a number of health factors that contributed to breathing issues already, the air choke proved to be far more effective in terms of unconsiousness.
Keep at it, it gets really fun at blue belt. make sure your school promotes based on ability, not time in grade.
Agree entirely with Reverend here even though we come from different backgrounds...it's a good rule of thumb for identifying any good martial arts school. It's one thing to use time in grade to determine when to have testing to potentially promote, but you want a school where you need to show you actually have the expected level of mastery over whatever it is you're expected to know at that belt in order to be promoted rather than simply "you've done x classes, you pretty much get your next belt". You'll get the most out of it that way