(This post is basically a preface for the much, much briefer next post.)
In 1786/1787, the Congress of the Confederation defined the dollar as being 375.64 grains of silver, based on the existing circulating Spanish dollar, which would continue to serve as alternative legal tender in the United States until 1857.
The Constitution and the Bill of Rights were ratified and came into effect between then and 1791.
The Constitution mentions the word dollar only twice, once in the original document and once in the Bill of Rights:
Article I:
Section. 9. The Migration or Importation of such Persons as any of the States now existing shall think proper to admit, shall not be prohibited by the Congress prior to the Year one thousand eight hundred and eight, but a Tax or duty may be imposed on such Importation, not exceeding ten dollars for each Person.
Amendment VII
In Suits at common law, where the value in controversy shall exceed twenty dollars, the right of trial by jury shall be preserved, and no fact tried by a jury, shall be otherwise re-examined in any Court of the United States, than according to the rules of the common law.
Here is what the Constitution has to say on the subject of **money.**
Section. 8. The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States; but all Duties, Imposts and Excises shall be uniform throughout the United States;
To borrow Money on the credit of the United States;
To coin Money, regulate the Value thereof, and of foreign Coin, and fix the Standard of Weights and Measures;
To provide for the Punishment of counterfeiting the Securities and current Coin of the United States;
To make all Laws which shall be necessary and proper for carrying into Execution the foregoing Powers, and all other Powers vested by this Constitution in the Government of the United States, or in any Department or Officer thereof.
Section. 10. No State shall enter into any Treaty, Alliance, or Confederation; grant Letters of Marque and Reprisal; coin Money; emit Bills of Credit; make any Thing but gold and silver Coin a Tender in Payment of Debts; pass any Bill of Attainder, ex post facto Law, or Law impairing the Obligation of Contracts, or grant any Title of Nobility.
The Constitution never defines the dollar or even declares that the dollar must be the monetary unit of the United States. Taxes on slaves and jurisdictional limits for jury trials are given in what would be presumed to be the 1786/1787 Continental defined silver dollar, but again, the Constitution never defines a dollar.
In 1792, CONGRESS passes the Coinage Act of 1792 and defines the dollar as 371.25 grains of silver. At a later point, a bimetallic standard is adopted, making the dollar convertible in gold or silver.
The Civil War arrives and Congress emits paper money to pay for it. Paper money depreciates and its constitutionality is challenged in court. The final result is the Legal Tender Cases of 1871. Paper money is constitutional.
We fought the battle of gold and silver during the 1880's and 1890's.
Then the arrival of the Federal Reserve (bills of credit tied to the overall government debt). FDR ended the gold standard in 1933. Nixon broke the final link in 1971.
Since then (1971), United States Dollar is an esoteric, theoretical term. There IS no definition of United States Dollar. It is not definable. It floats freely.
A dollar is worth what ever it happens to be worth on any given day, at any given moment in time.
And all of this is Constitutional.
The Constitution authorizes the Federal Government to coin money and prohibits the States from doing so. It forbids the States from emitting bills of credit, but is silent as to the Federal Government emitting bills of credit.
It forbids States from making anything but gold and silver a tender in payment of debt, but does NOT forbid the Federal Government from doing the exact same thing.
Since 1965, coins have been tokens only, bereft of intrinsic value exceeding the face value of the coin. Otherwise, people would be hoarding them and melting them for the metal, which was the reason for the change in 1964.
A Federal Reserve Note is not a United States Dollar, but is denominated in United States Dollars. It floats freely with the dollar and with the token coins.
There is not, never has been and never will be a Constitutionally defined "dollar."
The United States Dollar is currently an esoteric concept, changing value day by day and even hour by hour as more money is printed as as the total real wealth of society changes.
What is sought by some is to bring back is a silver dollar comprised of either 375.64 or 371.25 grains of silver and tied to the value of silver in the coin.
That ship sailed for good 112 years ago.