The Relation Between Justice and Virtue

At the end of the Wednesday lecture it was brought up that, according to Aristotle, a just person is one that is virtuous, in that a just person is one who practices a virtue that benefits the community as a whole. Temperance and an idea of "the greater good" are just qualities, while greedy personal gain and extremes are unjust qualities. However, Aristotle points out that "virtue is the same as justice, but what it is to be virtue is not the same as it is to be justice." I think this is supposed to mean that one can come to a virtue through unjust means, and thus make an injustice, which was brought up at the end of the lecture.

However, why is it an injustice? If a virtue is just, why would it ever be unjust, regardless of how they are accomplished. Aristotle claims that the worst person is one "who exercises his vice toward himself . . . . as well[ as toward others,]" while the best person is one that exercises a virtue toward the entire community. How then, could a person express a virtue, and have it still considered a virtue, while being an unjust person? Aristotle supposes that a person who is virtuous would be "brave .... temperate .... mild" and that "the correctly established law [instills] this correctly." This seems to imply that only someone who is following the law can be brave, temperate, and mild, and thus, are just qualities. But could not someone who is obviously "unjust" such also have such qualities? Or thinking about this on a multicultural scale, could what one country sees as brave, temperate, and mild be taken by another as cowardly, greedy, and aggressive? Are there examples of this in our lives today? Is that person still just in their society while being unjust in another? Is it possible for someone to occupy both the spaces of being just and unjust? Say if an American was seen as just in America and unjust in Canada, would the American be just because in their country, that is so? Or does justice extend past boarders, especially in an increasingly boarderless world? By all of this, I mean to say that the idea of virtues are subjective to a culture and can even subjective to a circumstance. Then, given the global world and all the cultures and values contained within it, can a "greater good" be established?