Found an interesting site with the law regarding Lady Liberty:
"In it (a) Section 2m Sixth reads: "The engraver shall prepare and engrave with the legal devices and inscriptions, all the dies used in the coinage of the mint and its branches." And Section 13 reads: "And be it further enacted, that upon the coins struck at the mint there shall be the following devices and legends; upon one side of each of said coins there shall be an impression emblematic of liberty, with an inscription of the word LIBERTY, and the year of the coinage; and upon the reverse of each of the gold and silver coins, there shall be the figure or representation of an eagle, with the inscription of United States of American, and a designation of the value of the coin; but on the reverse of the dime and
Half Dime, cent and
Half Cent, the figure of the eagle shall be omitted."