Medium of exchange was observed as early as Oresme, Copernicus and then in 1558 by Sir Thomas Gresham, that bad money drives out good in any marketplace (Gresham's Law states "Where legal tender laws exist, bad money drives out good money"). A more precise definition is this: "A currency that is artificially overvalued by law will drive out of circulation a currency that is artificially undervalued by that law." Gresham's law is therefore a specific application of the general law of price controls. A common explanation is that people will always keep the less adultered, less clipped, sweated, less filed, less trimmed coin,
Hard cases make bad law Oliver Wendell Holmes Jr. Its validity has since been questioned and dissenting variations include the phrase "Bad law makes hard cases", and even its opposite, "Hard cases make good law". The maxim dates at least to 1837, when a judge, ruling in favor of a parent against the maintenance of her children, said, "We have heard that hard cases make bad law." The judge's wording suggests that the phrase was not new then. Oliver Wendell Holmes Jr. made a utilitarian argument for this in his judgment of "Northern Securities Co. v. United States" (1904): Holmes's dissenting opinion in the case,