CARIIS - Lots of points. Sometime when I have more time I will respond to other parts, but I wanted to respond to the taser questions above.
Here is a link to the Police Chief Magazine study on level of use of force.
http://www.policechiefmagazine.org/magazine/index.cfm?fuseaction=display_arch&article_id=2204&issue_id=92010
There is a table that lists the use-of-force continuum adapted from the Orlando Police Department's Resistance and Response Continuum.
Suspect resistance
Officer use of force
1. No resistance 1. Officer presence
2. Verbal noncompliance 2. Verbal commands
3. Passive resistance 3. Hands-on tactics, chemical spray
4. Active resistance 4. Intermediate weapons: baton, Taser, strikes, nondeadly force
5. Aggressive resistance 5. Intermediate weapons, intensified techniques, nondeadly force
6. Deadly-force resistance 6. Deadly force
The definition of levels of resistance was also provided:
Passive Resistance The subject fails to obey verbal direction, preventing the officer from taking lawful action.
Active Resistance The subjects actions are intended to facilitate an escape or prevent an arrest. The action is not likely to cause injury.
Aggressive Resistance The subject has battered or is about to batter an officer, and the subjects action is likely to cause injury.
Deadly-Force Resistance The subjects actions are likely to cause death or significant bodily harm to the officer or another person.
So, I think we can all agree that IT's level of resistance was not any of 1-4. (None, Verbal, Passive or Active Resistance). The question remains was it Aggressive or Deadly-Force? Were his actions, as a trained MMA fighter, with some sort of weapon assaulting the agent, likely to cause injury or likely to cause death?
These are the thought processes the officer must have in a split second when the attack occurred. Did they make the right choice? I do not have enough information to know. Should they have used a taser? Depends on whether they thought IT was likely to cause death or significant bodily harm on the agent.