Cooper was born in Los Angeles where he enrolled in the Junior Reserve Officers' Training Corps at Los Angeles High School. He graduated from Stanford University with a bachelor's degree in political science. He received a regular commission in the United States Marine Corps (USMC) in September 1941. During World War II he served in the Pacific theatre with the Marine Detachment aboard USS Pennsylvania. By the end of the war he had been promoted to major. He resigned his commission in 1949, but returned to active duty during the Korean War, where he claimed to be involved in irregular warfare, and was promoted to lieutenant colonel. After the Korean War, the Marine Corps declined his application to remain on active duty. In the mid-1960s, he received a master's degree in history from the University of California, Riverside. From the late 1950s through the early 1970s, he was a part-time high school and community college history teacher.
In 1976, Cooper founded the American Pistol Institute (API) in Paulden, Arizona (later the Gunsite Academy). Cooper began teaching shotgun and rifle classes to both law enforcement and military personnel, as well as civilians, and conducted on-site training for individuals and groups from around the world. He sold the firm in 1992 but continued living on the Paulden ranch. He was known for his advocacy of large-caliber handguns, especially the Colt 1911 and the .45 ACP cartridge.
Cooper's modern technique defines pragmatic use of the pistol for personal protection. The modern technique emphasizes two-handed shooting using the Weaver stance, competing with and eventually supplanting the once-prevalent one-handed shooting style. The five elements of the modern technique are:
There are several conditions of readiness in which such a weapon can be carried. Cooper promulgated most of the following terms:
Bren Ten
Cooper, along with Michael Dixon and Thomas Dornaus, worked on the design of the Bren Ten pistol around the 10mm Auto, based on the Czech CZ 75 design. The cartridge was more powerful than both the 9×19mm Parabellum and the .45 ACP round.
The most important means of surviving a lethal confrontation, according to Cooper, is neither the weapon nor the martial skills. The primary tool is the combat mindset, set forth in his book, Principles of Personal Defense.
The color code, as originally introduced by Cooper, had nothing to do with tactical situations or alertness levels, but rather with one's state of mind. As taught by Cooper, it relates to the degree of peril you are willing to do something about and which allows you to move from one level of mindset to another to enable you to properly handle a given situation. Cooper did not claim to have invented anything in particular with the color code, but he was apparently the first to use it as an indication of mental state.
The following is from The Carry Book: Minnesota Edition, 2011:
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. As Cooper put it, "I might have to shoot."
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.
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.
Jeff Cooper simplified the Cooper color code in 2005 to :
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.
Cooper advocated four basic rules of gun safety:
All guns are always loaded. Even if they are not, treat them as if they are.
Never let the muzzle cover anything you are not willing to destroy. (For those who insist that this particular gun is unloaded, see Rule 1.)
Keep your finger off the trigger till your sights are on the target. This is the Golden Rule. Its violation is directly responsible for about 60 percent of inadvertent discharges.
Identify your target, and what is behind it. Never shoot at anything that you have not positively identified.