COL Cooper's color codes:

 Considering the principles of personal defense, we have long since come up with the Color Code. This has met with surprising success in debriefings throughout the world. The Color Code, as we preach it, runs white, yellow, orange, and red, and is a means of setting one’s mind into the proper condition when exercising lethal violence, and is not as easy as I had thought at first. 

There is a problem in that some students insist upon confusing the appropriate color with the amount of danger evident in the situation. As I have long taught, you are not in any color state because of the specific amount of danger you may be in, but rather in a mental state which enables you to take a difficult psychological step.

• White: Unaware and unprepared. If attacked in Condition White, the only thing that may save you is the inadequacy or ineptitude of your attacker. When confronted by something nasty, your reaction will probably be "Oh my God! This can't be happening to me."            
• Yellow: Relaxed alert. No specific threat situation. Your mindset is that "today could be the day I may have to defend myself". You are simply aware that the world is a potentially unfriendly place and that you are prepared to defend yourself, if necessary. You use your eyes and ears, and realize that "I may have to shoot today". You don't have to be armed in this state, but if you are armed you should be in Condition Yellow. You should always be in Yellow whenever you are in unfamiliar surroundings or among people you don't know. You can remain in Yellow for long periods, as long as you are able to "Watch your six." (In aviation 12 o'clock refers to the direction in front of the aircraft's nose. Six o'clock is the blind spot behind the pilot.) In Yellow, you are "taking in" surrounding information in a relaxed but alert manner, like a continuous 360 degree radar sweep.                                                                                                            
• Orange: Specific alert. Something is not quite right and has your attention. Your radar has picked up a specific alert. You shift your primary focus to determine if there is a threat (but you do not drop your six). Your mindset shifts to "I may have to shoot that person today", focusing on the specific target which has caused the escalation in alert status. In Condition Orange, you set a mental trigger: "If that person does "X", I will need to stop them". Your pistol usually remains holstered in this state. Staying in Orange can be a bit of a mental strain, but you can stay in it for as long as you need to. If the threat proves to be nothing, you shift back to Condition Yellow.
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• Red: Condition Red is fight. Your mental trigger (established back in Condition Orange) has been tripped. "If 'X' happens I will shoot that person" - 'X' has happened, the fight is on.

"In White you are unprepared and unready to take lethal action. If you are attacked in White you will probably die unless your adversary is totally inept.

In Yellow you bring yourself to the understanding that your life may be in danger and that you may have to do something about it.

In Orange you have determined upon a specific adversary and are prepared to take action which may result in his death, but you are not in a lethal mode.

In Red you are in a lethal mode and will shoot if circumstances warrant."