What Is It Illegal For The U.S. Treasury To Print On Currency?
Answer: Living Persons
Although it might simply appear to be a matter of national pride and design aesthetic that all U.S. currency with a person depicted on it carries the portrait of a long-deceased but historically significant American, it’s both national pride and a matter of law. Under the laws governing the production and printing of U.S. securities (which includes currency), it is illegal to feature portraiture of a living person on securities.
As such, the U.S. Treasury maintains a policy of selecting significant figures from American history that are well known to the public. The current set of portraits were originally chosen in 1928 and have been updated several times when new security features and layouts were introduced.
Image courtesy of the U.S. Department of Treasury.