The Coinage Act (of 1792 never repealed) provided that "the money (Gold/Silver/Copper) of account of the United States shall be expressed in dollars or units, dimes or tenths, cents or hundredths, and milles or thousandths." Concretely, "all accounts in the public offices and all proceedings in the courts of the United States shall be kept and had in conformity to this regulation."
Since the Constitution hasn't ever been amended to allow anything other than gold or silver coin to be payable for debt, and since the 1792 Coinage Act has never been repealed, one must wonder how the so-called State Courts collect fines in fiat currency UNLESS THEY AREN'T THE COURTS WE THINK THEY ARE !
If you were fined by a FRENCH COURT you would pay in French Francs. When you pay in FRNs you are paying the fine to a Federal Reserve Court.