What book is Lady Justice standing on?

In most depictions of Lady Justice, she is not standing on a book, but rather a pedestal.

there are different depictions of Lady Justice, however, of all of them she is not standing on a book. Usually she is standing on a pedestal just like the Statue of Liberty. Sometimes she is depicted as holding scales, books, being blind folded, or standing on a serpent. All of these have symbolic meaning.