I found this article to be interesting. It addresses the use of force and how the courts think.
I found in the article the court used the following reasoning to reach their conclusions:
1) Distance between the two persons
2) Which way the person being shot was facing
3) Whether or not a warning was shouted before the shot with taser
4) What weapon was the other person armed with
5) What was the other person doing that lead up to the incident
In the above incident, the driver was stopped for a traffic infraction. As what usually happens in these situations, the driver was upset and exercising his constitutional right to free speech. The officer then tased
the driver although he was unarmed, at a distance of 25 feet, and not facing the officer.
Although a TASER was used in this incident, it still is worthy of a firearms forum as you can see how the courts think and define an immediate threat.