This is a good question open to so much interpretation and misunderstanding. Unfortunately, due to the emotional connection when talking about justice, different forms of justice pervade our society. Justice is about obligation to our fellow man.
Justice signifies order and is what constitutes and contributes to the "human element." Acceptable behavior infers social responsibility and the "Golden Rule" that each person should "do unto others as you wish others to do unto you" is widely accepted but unfortunately not practised due to that very human element referred to. Thus, a just society is one in which personal feelings have no place, where decisions are reasoned and are not made irrationally or emotionally and where the members of that society understand the repercussions if they commit an offence and become subject to the laws of their particular country.
It is important to understand how culture and religion do form part of the whole picture. Christianity teaches compassion and forgiveness; Islam proposes honor as a prime component of justice and obeying the laws is paramount; Judaism practises the practical aspect of punishment that fits the crime. So there is already conflict as these three major religions themselves create different concepts of justice. All of them have their place but, especially when one aspect is preferred over the other, disagreement and disharmony result and some cannot see the "justice" as it does not fit their understanding of it.
Again, in a just society, it is crucial that people know and understand the consequences of their actions. This is why sanity (or insanity), age and maturity are all factors when recognizing justice.
In Lord of the Flies by William Golding the boys on the island, left to their own devices, descend into barbarism, and violence becomes their resolution for conflict situations with disastrous results. If those boys had been returned to civilization and tried for murder, what would have been a just result? The oldest of the boys was about 14 so a "just" society is likely to feel sorry for those boys and try to reintegrate them into society rather than punishing them.
Justice does have some basic elements that persist universally. No matter how harsh an upbringing, what religion or gender or religious beliefs a person has, fairness and a realization that the world does not revolve around one person or community ensures the very basic tenets of justice - before they are usurped when personal feelings, religion, etc interfere.
Impartiality is at the heart of justice. This requires the person metering out the justice to consider many factors. It is never enough to look at life globally; personal experience, personal circumstances and context are vital to ensure justice.
Everyone has seen the results of vigilantes taking justice into their own hands - impartiality is completely lost. Many so-called vigilantes are good, "God-fearing" (regardless of religion), people but emotional and personal issues prevent them from making practical decisions.
A just society is one where communication is key and involves
taking (of) the role of the other, self-consciously, in a social context. It is this ability possessed by human organisms
which allows objectivity to supercede the subjective view and ensure that peace that everyone is so desperate for. In other words, humans have not yet achieved that perfect "just society" but continue to strive towards it.