Justice belongs to a set. The medieval and Renaissance scheme of the cardinal virtues has four members, Justice, Temperance, Fortitude and Prudence, and the tarot trumps contain three of them. Justice, Temperance and Fortitude, the last under the name Strength, are all there in every standard pattern. Prudence is not.
This is a genuine and unresolved puzzle, and it has been argued over seriously. Some have proposed that the Hanged Man is Prudence, or that the Hermit is, or that the World is; others hold that the fourth virtue was simply never included, or was included in a lost variant. There is no manuscript that settles it. What can be said is that the absence is conspicuous, that a fifteenth-century Italian would have noticed it, and that any theory of the trumps as a coherent programme has to account for it. Theories claiming Egyptian or Kabbalistic design generally do not even try.
The number is also disputed. Justice is VIII in the older Italian and French patterns and XI in the Golden Dawn and Rider-Waite-Smith arrangement, which swapped it with Strength to make the zodiacal correspondences run in order. A statement about "the eleventh trump" therefore means different cards in different systems, and books frequently fail to say which they are using.
The image itself has been stable throughout: a seated crowned figure with a sword upright in one hand and a balance in the other. It is the standard personification, and unlike the Hermit or the Lovers it has not been reinterpreted out of recognition.