The term has several meanings. First, it can refer to a generally accepted, verified, proven, fundamental scientific relation. A law is a scientifically verified, cause-and-effect relation about the workings of the world. It has been tested and retested through the scientific method. The law of demand, law of increasing opportunity cost, and law of diminishing marginal utility are three fundamental (and extremely important) economic laws of nature. Second, the term can apply to legislative statutes.