Franzoni's relief features two birds. The first is an owl, a principal attribute of the Roman goddess Minerva, signifying wisdom. (As a war goddess, Minerva was the defender of just causes.) In Renaissance art, the owl is often perched on a stack of books to symbolize learning. But here, the owl is carved on the front leg of Justice's chair while, instead, an American eagle perches on law books. The eagle's head turns back toward Justice, whose head turns toward a nude, winged Genius. The guardian spirit of the new nation, the Genius holds and points to a tablet inscribed "The Constitution of the U.S." Behind the Genius's head is a sunburst, symbolizing Truth, whose light reveals all.

https://www.senate.gov/artandhistory/art/artifact/Sculpture_25_00001.htm