The celestial sphere reserved for just rulers in Dante’s Paradiso is Jupiter. Dante places souls who exercised justice as rulers in this sphere, the sixth of the heavenly spheres he visits.
The association draws on Jupiter’s traditional identity as the king of the Roman gods. In Paradiso XVIII, the souls of the just form letters spelling the Latin phrase “Love justice, you who judge the earth.” Their pattern then transforms into a giant imperial eagle, a symbol of righteous political authority and the Roman Empire.
Among the rulers Dante encounters are David, Hezekiah, Constantine, William II of Sicily, Trajan, and Ripheus the Trojan. Trajan and Ripheus are especially striking because Dante presents both pagans as saved through divine grace, challenging simplistic assumptions about who can attain blessedness.
A useful qualification is that the souls do not literally live in separate permanent compartments. Dante explains that all the blessed ultimately reside in the Empyrean, in God’s presence. The planetary spheres are visual arrangements shown for Dante’s understanding, with each sphere representing a particular virtue or spiritual quality. Jupiter therefore symbolizes justice, not a separate heaven outside the final divine realm.