I am starting this thread to discuss and gain more information about the use of Lawful Money.
12 US Code § 411. https://www.law.cornell.edu/uscode/text/12/411
"Federal reserve notes, to be issued at the discretion of the Board of Governors of the Federal Reserve System for the purpose of making advances to Federal reserve banks through the Federal reserve agents...They shall be redeemed in lawful money on demand at the Treasury Department of the United States...or at any Federal Reserve Bank."
DEFINITION OF 'LAWFUL MONEY'
Any form of currency issued by the United States Treasury and not the Federal Reserve System, including gold and silver coins, Treasury notes, and Treasury bonds. Lawful money stands in contrast to fiat money, to which the government assigns value although it has no intrinsic value of its own and is not backed by reserves. Fiat money includes legal tender such as paper money, checks, drafts and bank notes.
INVESTOPEDIA EXPLAINS 'LAWFUL MONEY'
Oddly enough, the dollar bills that we carry around in our wallets are not considered lawful money. The notation on the bottom of a U.S. dollar bill reads "Legal Tender for All Debts, Public and Private", and is issued by the U.S. Federal Reserve, not the U.S. Treasury. Legal tender can be exchanged for an equivalent amount of lawful money, but effects such as inflation can change the value of fiat money. Lawful money is said to be the most direct form of ownership, but for purposes of practicality it has little use in direct transactions between parties anymore.
From the Federal Reserve website
"What is lawful money? How is it different from legal tender?
"Lawful money" is a term used in the Federal Reserve Act, the act that authorizes the Board of Governors of the Federal Reserve System to issue Federal Reserve notes. The Act states that Federal Reserve notes "shall be obligations of the United States and shall be receivable by all national and member banks and Federal reserve banks and for all taxes, customs, and other public dues. They shall be redeemed in lawful money on demand at the Treasury Department of the United States, in the city of Washington, District of Columbia, or at any Federal Reserve bank." The Act did not, however, define the term "lawful money," but up until 1913, the only currency issued by the United States that was legally recognized as "lawful money" was various issues of "demand notes" (subsequently known as "old demand notes") and "United States notes" authorized by Congress during the Civil War.
At the time, some currency was not considered legal tender, although it could be used by national banking associations as "lawful money reserves." Thus, the term "lawful money" had a broader meaning than the term "legal tender."
In 1933, Congress changed the law so that all U.S. coins and currency (including Federal Reserve notes), regardless of when issued, constitutes "legal tender" for all purposes. Federal and state courts since then have repeatedly held that Federal Reserve notes are also "lawful money." Milam v. U.S., 524 F.2d 629 (9th Cir. 1974), is typical of the federal and state court cases holding that Federal Reserve notes are "lawful money." In Milam, the United States Court of Appeals for the Ninth Circuit reviewed a judgment denying relief to an individual who sought to redeem a $50 Federal Reserve Bank Note in "lawful money." The United States tendered Milam $50 in Federal Reserve notes, but Milam refused the notes, asserting that "lawful money" must be gold or silver. The Ninth Circuit, noting that this matter had been put to rest by the U.S. Supreme Court nearly a century before in the Legal Tender Cases (Juilliard v. Greenman), 110 U.S. 421 (1884), rejected this assertion as frivolous and affirmed the judgment.