The use of the national motto on both U.S. coins and currency notes is required by two statutes, 31 U.S.C. 5112(d) (1) and 5114(b), respectively. The motto was not adopted for use on U.S. paper currency until 1957. It first appeared on the 1935G Series $1 Silver Certificate, but didn’t appear on U.S. Federal Reserve Notes until the Series 1963 currency. This use of the national motto has been challenged in court many times over the years that it has been in use, and has been consistently upheld by the various courts of this country, including the U.S. Supreme Court as recently as 1977.
The Department of the Treasury and the Department of Justice intend to actively defend against challenges to the use of the national motto. In 1992, a challenge was filed and successfully defeated in the U.S. District Court for the District of Maryland.