What Is Lawful Money?
Lawful money is any form of currency issued by the United States Treasury and not the Federal Reserve System. It includes gold and silver coins, Treasury notes, and Treasury bonds. Lawful money stands in contrast to fiat money, in 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 banknotes.
Lawful money is also known as "specie," which means "in actual form."