Justice & Violence

When someone is asking for "justice" against any wrongdoing, most would assume he implies -as a victim - to use violence to satisfy a legitimate thirst for revenge. If he doesn't use violence himself, he will ask the society to do it for him with the death penalty (if necessary).
Similarly, when a country asks for "justice" against another country, other countries often fear that this country really means to start a war.
There is therefore a kind of paradox that peace-loving people (and nations) would fear "justice-loving" people as potential trouble-makers. There would be an opposition between the "cowards" who prefer peace to justice and the "hawks" who prefer justice to peace.

Let us think about awful crimes such as cold-blooded murders & rapes etc.
At the international level, a "just war" is often started when there is an agression, or (more controversially) the risk that an agression takes place.

In each case, those who seeks to use violence (death penalty / war), are doing so in the name of justice. Those who opposes the use of violence are understood to prefer peace to justice.

There are a few problems with this kind of thinking.
First, crimes or international agressions often take place in a context where justice is nowhere to be found. In other words, these crimes and conflicts may be the effects of the lack of justice. By using more violence, the victims will not solve the lack of justice which is the real cause for these wrongdoings.
Second, even though these crimes have been commited without any good reasons to justify them, the use of violence may jeopardize the return of justice. Why?
a. Victims will not feel any better once criminals are killed. The dead won't come back to life.
b. People always have a capacity to be "reasonable persons" and change their previous "evil ways". To deny these people a second chance is not the right thing to do.
c. The use of violence may strike totally innocent people. What comes next when these "new victims" ask for justice? Bertrand Russel used to say that "war does solve problems, but it solves them the wrong way".
Third, justice implies to have a fair trial where the motives of the criminals are well understood. What should come as "justice" is a form of punishment that keeps potential victims safe (by keeping criminals in jail, or "rogue" nations under international pressure) but this punishment must also prepare for peace by seeking to educate the criminals.

There is therefore a constant relationship between peace and justice. A lack of peace brings a lack of justice (violence/war brings injustice). A lack of justice also brings a lack of peace (the more there is injustice, the more violence/war will appear justified).
However, a peaceful environment appears to be sustainable when people acknowledge a rule of law ensuring a sense of justice.

At community level, avoiding violence means having a credible system of laws and enforcement. A system of law must come from a legitimate government with legitimate courts of justice (where judges and lawyers are not corrupt). Off-course, a primary requirement is non-corrupt police force.
At international level, avoiding violence means a credible international system of laws and enforcement to solve conflicts before war is declared. This should be the role of the United Nations.

With the right understanding of this close relationship between injustice and violence, it becomes common sense to say that those asking for justice must stick to non-violence. Non-violence is really relevant in the face of injustice. Non-violence is absolutely the norm in a context of "justice" anyway.

The limits of non-violence are found during a situation where it's a matter of life and death to use violence. Once again this is controversial and depends on each context. Gandhi used to say that practicioners of non-violence must be ready to die without using violence "in the name of justice". What he probably meant is if the use of violence to save our own lives implies putting other innocent people at risk, we should avoid defending ourselves to avoid more injustice to others. This is controversial as our death means we won't be able to protest injustice anymore. Is it ethical to accept to sacrifice our life when we don't deserve to die?

The fear of dying and being harmed is however a primary cause of violence.

To conclude, those who pretends to defend "justice" should abstain to use violence whenever it is possible. Violence is really the mean used by those who accept injustice.