legal measures
Note to the The Veins Of Wealth from Unto This Last by John Ruskin

The disputes which exist respecting the real nature of money arise more from the disputants examining its functions on different sides, than from any real dissent in their opinions. All money, properly so called, is an acknowledgement of debt; but as such, it may either be considered to represent the labour and property of the creditor, or the idleness and penury of the debtor. The intricacy of the question has been much increased by the (hitherto necessary) use of marketable commodities such as gold, silver, salt, shells, etc., to give intrinsic value or security to currency; but the final and best definition of money is that it is a documentary promise ratified and guaranteed by the nation to give or find a certain quantity of labour on demand. A man's labour for a day is a better standard of value than a measure of any produce, because no produce ever maintains a consistent rate of productibility.