Justice, originally Card VIII, has been associated with number XI with the global success of the Rider Waite system. It is the card of fair decisions, balance and legal matters.
Harsh but fair, this card speaks of cosmic justice as well as human justice. Everyone gets what they deserve in the end.
Bad actions lead to inevitable punishment.
It is the card of official and legal matters. Contracts are signed, conflicts are settled.
You may not always understand why something is happening, but Justice assures you that things are unfolding as they should. In a fair way.