Justice

"Justice", at its base, means "to be just, fair". More commonly however, the meaning of justice is to punish a criminal that has done something wrong in a suitable manner that fits their crime.

Justice, in this sense, can be served by a criminal in many ways from receiving a fine, serving time in prison or execution, to name a few. The classic view of how a criminal should 'serve justice' is thought of as "an eye for an eye", which means if they have done something wrong, they deserve a punishment as great as the crime they committed. If a killer murders someone, then according to this term, it means they themselves should face death as a suitable form of justice.

One Piece Justice
The thing called 'justice' changes its shape... Depending on where you stand. -Kuzan on Justice to Saul.

Justice has been used many many times in the series; the CP9 use this term against Iceburg, the Marines use this term to catch pirates and criminals. Justice is used in an archetypal pattern often at times (e.g. someone would talk about doing things "In the name of justice" or "ridding the world from evil"). A common theme is that corrupt members of Marines and CP9 often use Justice as justification for their actions, putting every inhumane thing they've done as a necessary evil to preserve peace to the world, this has often led people (most of them pirates) to react with disgust at their behaviour.

Absolute Justice
...Absolute Justice... Sometimes drives a man insane. -Kuzan on Justice; in regard to Sakazuki's actions at Ohara Absolute Justice (絶対的正義, Zettai-Teki Seigi) is the belief that many marines hold.

What is Absolute Justice?
Marines following the rule of Absolute Justice will be noted to display some or all of the following views:
 * 1) Anyone connected to criminals, no matter who they are, can be arrested even if they have not done anything.   Even if the criminal is family, they must be captured or killed. Particularly with dangerous criminals, women carrying their children or the children of the criminal, can be arrested or killed to prevent the possibilities of the child continuing their parents' actions.
 * 2) All individuals noted to have done illegal activities or criminal acts will be reported to Marine HQ and issued bounties, based the known information on their threat level. Regardless of the circumstances.
 * 3) Raising the Jolly Roger, mentioning, or being associated with pirates can be taken as a criminal offense.
 * 4) Any country caught harboring pirates can have further actions taken against them.
 * 5) Destroying an island to eliminate a problem is an option.
 * 6) Innocent lives can be taken to prevent the possibility of a criminal escaping.
 * 7) Any Marine who hesitates to take action against a criminal as ordered can face punishment.
 * 8) Criminals are used by the World Government to serve their purposes and to restrain their further criminal activities, such as the Shichibukai and Oimo and Kāshī.
 * 9) Slavery is ignored as it is seen as an effective means to handle criminals.

Moral Justice
Moral Justice: Much like "human justice".

What is Moral Justice?
Marines following the rule of Moral Justice will be noted to display many or all of the following views:
 * 1) Giving someone a warning without charges being pressed against them.
 * 2) Refusing to receive credit for criminals who have stopped other criminals.
 * 3) Refusing to capture criminals, sparing criminals, or ordering other Marines not to arrest criminals.
 * 4) Allowing a criminal to join the Marines so long as they forget their past.
 * 5) Refusing to obey orders on moral grounds.
 * 6) Questions the orders of a superior officer.
 * 7) Dismissing Marines or other member of the law who are too cruel in their ways.

The Opinion of the word "Justice"
Pirates are evil!!? Marines are righteous!!? These terms have always changed throughout the course of history...!! Kids who have never seen peace and kids who have never known war have different values!!! Those who stand at the top determine whats right and wrong!!! This very place is neutral ground!!! Justice will prevail you say!? But of course it will!!! Whoever wins this war becomes justice!!!

-Doflamingo on Justice While currently, only two types of justice are shown in the series Marines may choose to display signs of either form of justice based on their own interpretations or opinions. Some example of different opinion-based ideas on justice include Aokiji who declared he served a "Lazy Justice", Rob Lucci who claimed to serve a "Dark Justice" and Smoker who told Tashigi to create her own "personal justice". In the CP9 Mini series, Rob Lucci was seen to have done an "Excessive Justice" to the Candy Pirates. The extreme nature of his attack against them horrified the citizens that witnessed his strike.

Doflamingo, though a former pirate and Shichibukai, is not without some opinion in regarding what is and isn't justice, but he himself doesn't seem to care for it. He truly believes justice is whoever is in charge deem it to be and regards the outcome of the Whitebeard and Marine War will have the the right to say what is and isn't justice.

The Doctrine of "Absolute Justice"
The Marines follow a strict motto of "Absolute Justice" (絶対正義 Zettai Seigi), when it comes to prosecuting those who violate the government's laws. It is a central tenet of Marine doctrine, to the point where the word "Justice" (正義 Seigi) is emblazoned on the uniform coats of all commissioned officers. Pirates have been especially singled out by the Marines as a major threat to order. They are considered criminals regardless of whether they have committed any crimes other than raising the Jolly Roger. Civilians, too, are targeted by the prohibition against piracy: persons known to have associated with pirates are barred from entering the Marines (there are notable exceptions), and providing aid or comfort to pirates is a serious crime, especially if they are well-known bounty heads.

It's not known why the World Government supports absolute justice as much as it does nor where the ideals centered around it originate from, however Vice-Admiral Onigumo best described it as willing to sacrifice anything to defeat what is defined as "evil", though it does ensure that the majority of the world is held under the World Governments thumb effectively giving them absolute control of the world. However, this thought of Absolute Justice is seen to be clearly ignored if a World Noble is committing the acts.

One of the ongoing themes of One Piece is the misapplication of the principle of "justice" by the Marines. While the Marines wish to maintain law and order by apprehending criminals, the techniques that it (or at least some of its members) use can often be no better (or in some cases even worse) than the pirates they seek to wipe out, trampling the rights or needs of civilians in order to pursue its own ends. They are also shown to willingly sacrifice the lives of other Marines in attempts to pursue absolute justice, often sacrificing large numbers for the sake of one or two criminals. Thus, proving that, judging from their morally-questionable actions, the Marines are just as bad as, if not worse than, the enemies they fight.

The Failure of "Absolute Justice"
The failures so far of this rule have been proven constantly and in many cases led to the opposite happening of what they were intending:
 * An unknown amount of women and child were killed in their witch hunt for Roger's child. Rouge was aware of the child hunt thus delayed childbirth as long as possible, Garp protected Ace after his birth as he promised to Roger.
 * A whole ship of civilians were killed during the Ohara incident in case one of the Ohara scholars slipped on board. Robin, the only scholar trying to board the ship, had been put off boarding the ship because of the others' hatred for her. When the ship was destroyed, Aokiji initially led to help Robin escape after being disgusted by his fellow Vice-Admirals actions, an irony in itself as Aokiji intended to end the life of Robin himself up until it happened.
 * At Enies Lobby, shooting the ship of Marines led one to protest only to be shot at for his protests. The target of the blasts was Luffy who Rob Lucci was fighting. However the only target to be taken out was the ship itself and its crew and Luffy got off the ship without a problem. Thus the death of the crew and the soldier were directly a result of the Vice-Admiral's use of Absolute Justice.

Punishments
The One Piece world has various punishments for crimes. Policemen who abuse their position like Lafitte risk loosing their position, and can even be banished from a particular area. In a more serious case, they can even be imprisoned and brought in as a criminal themselves. Criminals who gain a bounty can risk bounty hunters chasing them, or in more serious cases Marines. Those in the grand line also can risk being taken by kidnapping groups and sold off. Marines who capture a criminal may hold onto them until they are taken to a more suitable prison, like Impel Down. Some will spend a brief moment here, but most will spend the remainder of their lives here, even dying in the extreme nature of Impel Down's levels. For those who are deemed too much, they are made an example of to put others off doing activities similar to what they did. In this case, death.

The most popular method of execution seen in the One Piece world was used on Gold Roger, Norland and Portgas D. Ace. It involves placing a criminal on a high execution platform, above the heights of most individuals, usually in a high populated area where the normal citizens can see the criminal be punished. From here everyone can watch as two executioners each stab the criminal with a long blade.

Another, less spectacular, metod is shooting by a firing squad. It seems to be used on less prominent criminals like Nugire Yainu who was executed under the name of Captain Kuro.

The most notable problem however is that the innocent can be punished by accident, although the authorities in the One Piece world seem to care little about this. The Just Eleven Jurymen in particular had a reputation for announcing any criminal who entered Enies Lobby as "guilty". The Jurymen themselves were criminals due for their own execution and had sown to take as many criminals down with them. On top of this, the "3-headed" judge Baskerville would pronounce both verdicts of innocent(left head) and guilty (right head), but ultimate decide (with its middle head) that the criminal was to die anyway. Thus it would seem to make sure no criminal escaped the authorities would turn to killing even the innocents, which diminishes the point of punishing criminals in the first place.

Trivia

 * Though extreme, the act of punishing those who have anything to do with piracy was also common in the real world, hence why many pirates used nicknames or epithets to protect those around them.