<P> In 1971, research chemist Stephanie Kwolek discovered a liquid crystalline polymer solution . Its exceptional strength and stiffness led to the invention of Kevlar ®, a synthetic fibre, woven into a fabric and layered, that, by weight, has five times the tensile strength of steel . In the mid-1970s, DuPont the company which employed Kwolek introduced Kevlar . Immediately Kevlar was incorporated into a National Institute of Justice (NIJ) evaluation program to provide lightweight, able body armor to a test pool of American law enforcement officers to ascertain if everyday able wearing was possible . Lester Shubin, a program manager at the NIJ, managed this law enforcement feasibility study within a few selected large police agencies, and quickly determined that Kevlar body armor could be comfortably worn by police daily, and would save lives . </P> <P> In 1975 Richard A. Armellino, the founder of American Body Armor, marketed an all Kevlar vest called the K - 15, consisting of 15 layers of Kevlar that also included a 5" × 8" ballistic steel "Shok Plate" positioned vertically over the heart and was issued US Patent #3,971,072 for this innovation . Similarly sized and positioned "trauma plates" are still used today on the front ballistic panels of most able vests, reducing blunt trauma and increasing ballistic protection in the center - mass heart / sternum area . </P> <P> In 1976, Richard Davis, founder of Second Chance Body Armor, designed the company's first all - Kevlar vest, the Model Y . The lightweight, able vest industry was launched and a new form of daily protection for the modern police officer was quickly adapted . By the mid-to - late 1980s, an estimated 1 / 3 to 1 / 2 of police patrol officers wore able vests daily . By 2006, more than 2,000 documented police vest "saves" were recorded, validating the success and efficiency of lightweight able body armor as a standard piece of everyday police equipment . </P> <P> During the 1980s, the US military issued the PASGT kevlar vest, rated at NIJ level IIA, being able to stop pistol rounds (including 9 mm FMJ) and fragmentation . West Germany issued a similar rated vest called the Splitterschutzweste . </P>

When did police start using bullet proof vests