The concept of justice versus just us entails that a certain social group, either by creed, race, gender, or lifestyle, is superior to every other group coexisting within one same society. As a result, being a part of this dominant group grants exclusive rights and privileges that the other groups will never gain, or are less prone to obtain. Often, this "just us" group is a group that you are born into.
A brief example of "justice versus just us" occurs within the Indian caste system, although this hierarchical system is not limited to India. In this type of social construct, if you are born to the "right" caste, your social rights and privileges are guaranteed for life. In a drastic contrast, if you are born into what has been historically recognized as the lowest of the caste, then you are deemed an "Untouchable". As far as the "untouchables" goes, even the government of India admits to the consistent and crass discrimination that is suffered by this very unfortunate group. As you can see the "just us" is often a very defined, very protected, and very long-standing group.
In the poem "Suicide Note", the main character is a young college student of Asian heritage who has lost the faith in herself and claims to be
not good enough, not strong enough, not good enough
Yet, the subtle entrance of the "justice versus just us" concept can be clearly found in these verses
If only I were a son, shoulders broad
... I would see the light in my mother's
eyes, or the golden pride reflected
in my father's dream
of my wide, male hands worthy of work
Notice how, in this case, the "just us" is the male gender. The suffering young woman is convinced that her problems are partly a result of what she believes to be the "flaw" of her gender: weakness. She thinks that women are less strong, and make their parents less proud than if they were men. She goes on saying how much happier she would be having "stronger hands", and how she would "swagger" in freedom, basically. There is an evidently strong assumption from the part of the woman that men are, indeed, much better, much more confident, and much happier.
I would swagger through life
muscled and bold and assured, drawing praises to me
like currents in the bed of wind, virile
We can conclude then that, in this woman's culture, men occupy a superlative social standing than women; that justice is not equal to all, and that privileges and benefits are often bestowed upon the "just us"; men.
It is also safe to conclude that the woman is merely assuming that being born a man is better simply because that is the experience that she has lived through growing up in a male-dominated society. Hence, the "just-us" group that she witnessed growing up must have definitely superimposed their dominance in a very big way for her to think this way.