"Justice has to be declared as an essential principle of human organisation."

Rereading your post days later perhaps I should have added to mine that justice has long been essential for the proper functioning of society.

Likely the quintessential example of just how long justice has been considered important to societies comes from a text written over two millennia ago—Plato's Republic.

Plato considers justice so significant that he begins in Book I to ask 'What is Justice?' and then goes on to explain why it is so important to society. Therein, he constructs one of the most satisfying and logical debates ever written.

Plato pits the sophist Thrasymachus up against the philosopher Socrates in a battle of wits. Thrasymachus opens with a salvo of reasons why justice is everyman for himself and bit by bit Socrates systematically demolishes Thrasymachus' arguments and rebuilds them into the notion that justice is much broader and more important concept—a matter for society as a whole to embrace rather than the sophist's narrow, selfish view which only has self-interest in mind.

This is a wonderful dialogue and I've read it many times since I first learned about it in philosophy decades ago. And I'd posit that it has survived for so long throughout the ages because so many consider what it has to say about justice as being too important for it to be lost.

Not only do I consider Plato's take on justice just as important now as when it was written but also this cleverly constructed dialogue ought to be taken as a template for how political debate should be conducted both on and off the internet instead of the disorganized rabblerousing where only the loudest and outrageous are heard, as is so often the case nowadays.

There are many copies of the Republic in English on the internet, perhaps the best known is Benjamin Jowett's translation/revision of 1888 (it's the version I learned from). Here's a link to that copy on Project Gutenberg: https://www.gutenberg.org/files/55201/55201-h/55201-h.htm

Edit: this MIT version is better formatted for smartphones and other mobile devices but it's sans intro (Gutenberg and the MIT download versions do have the full intro, foreword etc., but that's not necessary except for diehards and students): http://classics.mit.edu/Plato/republic.2.i.html