During the initial years when Kevlar vests were first deployed by both military/police most wore their vests outside due to the size and weight of them, especially any ballistic body armour that had ballistic panels over Level IIIA protection level, as the armor was usually too heavy and cumbersome to be worn underneath clothes, closer to the body, like concealable armor.  Once vests became lighter and more compact, local law enforcement started wearing concealable body armor under the uniforms for a more professional look, without the sacrificing protection.  Today, the Kevlar vest and external vest carriers can once again be found on the outside of the wearer’s uniform for added protection- upgradable to hard armor rifle protection- and allows wearer to shift positioning of his equipment and pouches from the duty belt to the vest carrier for better weight distribution.