What is an Adversary System?

Mary McMahon
Mary McMahon

An adversary system is a legal system in which cases brought before the court are presented by two opposing sides before a neutral panel of individuals which can include a judge and jury. Once both sides have argued their cases, the panel determines the facts of the case and any appropriate actions which need to be taken. This is in contrast with an inquisitorial system, in which cases brought to court are tried in front of a panel of people who act as questioners in addition to deciders. Both systems have advantages and disadvantages and there has been much debate about whether or not one is superior to the other.

A panel of individuals determines the outcome of a case based on witness testimony and evidence presented by opposing sides in an adversary system.
A panel of individuals determines the outcome of a case based on witness testimony and evidence presented by opposing sides in an adversary system.

Common law nations commonly use an adversary system, and the roots of this system are quite ancient. By contrast, nations which rely on civil law tend to be more likely to utilize an inquisitorial system, due to differing approaches in legal style, and this legal system is also quite venerable. Some nations utilize elements of both systems.

Common law nations commonly use an adversary system.
Common law nations commonly use an adversary system.

Adversarial systems, as they are also known, are sometimes criticized for setting up a system in which sides on a case are obliged to contest with each other. Some critics believe that the adversary system encourages deception and a variety of questionable legal tactics because the goal is to win at all costs, in contrast with an inquisitorial system which relies on a factfinding panel to determine the truth.

In an adversary system both sides are allowed to present evidence and witnesses to support their positions. The opposing side can cross examine witnesses, analyze the evidence independently, and challenge arguments made before the court. The goal of this process is to present all of the facts of the case for the benefit of the judge and jury, who can sift through the material to decide what happened and who, if anyone, should be held responsible.

The judge and jury are expected to remain impartial and are chosen in part using criteria which are designed to eliminate people who might have a bias in the case. The idea is that by presenting the contest to people without an interest in the outcome, people can receive fair trials because the facts will be evaluated objectively. In actuality, the situation in an adversary system can be much more complicated, and lawyers on both sides in the adversary system can use rhetorical and legal tricks to influence opinion, which may in turn have an impact on the outcome of the trial.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@Latte31 - You make a good point, but I have to say that while the adversary system of justice is not ideal it is still better than the inquisitorial system.

In the inquisitorial system the judge plays a larger role and may have a bias in one form or another. The judge is the one determining who is guilty based on his line of questioning. So what happens if the judge takes a secret bribe? This happens a lot all over the world.

At least when you look at the differentness between an adversarial system vs. inquisitorial system you can conclude that you have a better chance at a fair trial with the adversary system because not only does your side get to put out all of your facts with respect to the case, but you will also be judged by an independent jury of your peers.

Juries are usually very impartial and any juror not adhering to these rules will be dismissed and another juror will step in.

In the inquisitorial system you are really at the mercy of the judge and you have to hope that he sides with you. I think judges are people like everyone else and they form their own bias which will not be fair to some defendants.


@Cafe41 -I agree with you and along the same point I wanted to say that this is why people are wrongfully convicted of crimes that they did not commit. I was watching a television show about a man that was sent to prison for armed robbery.

Since the defendant had a criminal past and he had to rely on a public defender he was convicted. The victim gave eye witness testimony that this man was the suspect that tried to rob him at his store, but he was picked out of line up in a book.

He said that the suspect was 6’1 and the jury heard this circumstantial evidence and convicted the man. Since he had a previous criminal record this conviction sent him to prison for twenty years. Later on, his wife with the help of a private investigator was able to find out who actually committed the crime and the jailed man was later released and the other suspect was arrested.

The suspect was 5’8” nowhere near the 6’1” description that the victim initially gave the police. This is what can happen in the adversarial system which is why we have to figure out a way to prevent tragedies like this from happening.

The jury was influenced by the criminal past of the defendant and the eye witness testimony of the victim. The fact that the criminal past was able to be brought up already set up this defendant for failure. The criminal procedures should be fair and they usually are, but they weren’t in this case.


I understand the reason behind the adversarial system of justice but I do see the pitfalls too. It really amounts to who has the better lawyer.

If you think about it this is unfair because a wealthy person with unlimited means can have a team of lawyers and will probably face an acquittal because the odds are more favorable if you have that many high powered attorneys working on your case.

The regular Joe might have to go with a public defender that is usually overworked and has limited resources. The regular Joe has a higher chance of being convicted not because he may be guilty but because his lawyer does not have the manpower and the funds to be as detailed as a private attorney would.

Sometimes innocent people get convicted because their attorney was not as good. That does not seem fair to me.

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