Commodity money as a theoretical backing for federally issued "gold certificates" to substitute for the gold. Between 1933 and 1970 (when the U.S. officially left the gold standard), one U.S. dollar was technically worth exactly 1/35 of a troy ounce (889 mg) of gold. However, actual trade in gold bullion as a precious metal within the United States was banned after 1933, with the explicit purpose of preventing the "hoarding" of private gold during an economic depression period in which maximal circulation of money was desired by influential economists. This was a fairly typical transition from commodity to representative to fiat money,
Simple commodity production persists within industrialised capitalist economies in the form of self-employment by free producers. Capitalist firms sometimes contract out specialised services to self-employed producers, who can produce them at a lower cost, or provide a superior product. In Marxian political economy, simple commodity production also refers to a hypothetical economy used to interpret some of Karl Marx's insights about the economic laws governing the development of commodity trade: it refers to a market economy in which all producers own the resources (including the ability to work) that they use in production. No-one is a proletarian, selling his or her labor power