<P> These "Chicken Plates" were made of either boron carbide, silicon carbide, or aluminium oxide . They were issued to the crew of low - flying aircraft, such as the UH - 1 and UC - 123, during the Vietnam War . </P> <P> In 1969, American Body Armor was founded and began to produce a patented combination of quilted nylon faced with multiple steel plates . This armor configuration was marketed to American law enforcement agencies by Smith & Wesson under the trade name "Barrier Vest ." The Barrier Vest was the first police vest to gain wide use during high threat police operations . </P> <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>

When was kevlar first used as body armor