Coca is a plant and should be legal. It makes little sense to make a plant illegal. Coca has use in the medical field and can be prescribed, but is rarely used for it outside of certain surgeries. Coca has long been used, in a number of ways, for energy and focus. Several of these ways, such as coca tea and chewing the leaves are little to no risk to the user. No more than coffee anyway.
Not only is the coca plant used in the production of one of my favorite beverage, Coca Cola, it is also used in making of many different medicines, is rich in nutritional properties when left in its natural state and is important to some religions in Andes mountains area. Traditionally, coca leaves are prepared either to chew or as tea and has no addictive properties in its natural state.