The constitution defines what it just. Laws can be unjust.
The constitution is a law. It is the supreme law, by its own definition.
Just as an exercise, do you think you can write down my counterargument? It's not hard to see what I'll probably say.
edit: here, I'll help you. For part (a) of this question, list four different meanings of the word 'law', and give an example of each. For part (b), describe what the word 'just' means when applied to each definition from part (a). (Hint: they are all different.)
I wasn't aware that the state defines what is just and what is not. Does that mean that there are no unjust laws?