The adversarial legal system is widely used in common law jurisdictions around the world. In theory, under this system two opposing sides, represented by lawyers, present their cases to an impartial judge or jury, who then decides the outcome of the case based on the evidence presented.

This system is often presented as a way to ensure both sides can vigorously advocate for their positions and that the truth is ultimately revealed through the adversarial process. However, critics argue that the adversarial system can be flawed and it may not always promote justice. If it does not, whose interests does it serve?

In England and Wales, we have a predominantly adversarial system of justice. Our criminal and civil trials are based on the adversarial system. The same is true in other common law countries whose legal systems are, to a greater or lesser extent, derived from ours. In describing the essential elements of the English adversarial system, I can’t improve on the words of Lord Denning in Jones v National Coal Board [1957] 2 QB 55:

“In the system of trial which we have evolved in this country, the judge sits to hear and determine the issues raised by the parties, not to conduct an investigation or examination on behalf of society at large, as happens, we believe, in some foreign countries. Even in England, however, a judge is not a mere umpire to answer the question ‘How’s that?’ His object, above all, is to find out the truth, and to do justice according to law; and in the daily pursuit of it the advocate plays an honourable and necessary role. Was it not [Lord Chancellor Eldon] who said in a notable passage that ‘truth is best discovered by powerful statements on both sides of the question’?… and [Master of the Rolls Lord Greene] who explained that justice is best done by a judge who holds the balance between the contending parties without himself taking part in their disputations? If a judge, said Lord Greene, should himself conduct the examination of witnesses, ‘he, so to speak, descends into the arena and is liable to have his vision clouded by the dust of conflict’…

Yes, he must keep his vision unclouded. It is all very well to paint justice blind, but she does better without a bandage round her eyes. She should be blind indeed to favour or prejudice, but clear to see which way lies the truth: and the less dust there is about the better. Let the advocates one after the other put the weights into the scales – the ‘nicely calculated less or more – but the judge at the end decides which way the balance tilts, be it ever so slightly. So firmly is all this established in our law that the judge is not allowed in a civil dispute to call a witness whom he thinks might throw some light on the facts. He must rest content with the witnesses called by the parties… So also it is for the advocates, each in his turn, to examine the witnesses, and not for the judge to take it on himself lest by so doing he appear to favour one side or the other… especially. and it is for the advocate to state his case as fairly and strongly as he can, without undue interruption, lest the sequence of his argument be lost…”

We can identify certain key features which characterise the English adversarial system of justice:

• First, as we just heard from Lord Denning, it is for the parties to decide which witnesses to call, and how to present their cases. The judge serves as a neutral arbiter. Although judges can and do intervene during argument and ask questions of witnesses, it is considered inappropriate for a judge to intervene too much and to assume the role of an advocate.
• Second, a lot of emphasis is traditionally placed on oral evidence. Parties who rely on a witness are generally expected to call them to give oral evidence in court and opposing counsel has the right to cross-examine the witness. Cross-examination by a skilled advocate is seen both as an opportunity for witnesses to answer criticisms of their evidence and as a vital tool in getting to the truth.
• Third, there are technical rules of evidence. Just because evidence is relevant doesn’t always mean it is admissible. Nowadays, the rules of evidence in civil cases have been significantly relaxed, but in criminal cases the rules of evidence continue to play an important role.
• Fourth, the system, at least in theory, strives for equality of arms. The prosecution and defence in a criminal case or the claimant and defendant in a civil case are in theory supposed to be on a level playing field. In reality, we all know that this is not always the case, especially when one party is represented by skilled lawyers and the other is unrepresented. But equality of arms is the theoretical underpinning of our system, even if it is sometimes more honoured in the breach than the observance.
• Fifth, what follows from these principles is that the adversarial system places a lot of reliance on the professional skills of lawyers. The adversarial system is at its fairest when the lawyers on each side are evenly matched. If a lawyer makes errors, their opponent can and often does exploit those errors.

The flaws

One main criticism is that the adversarial system can be overly focused on winning and losing, rather than on finding the truth and promoting justice.

In an adversarial system, lawyers are often motivated by a desire to win their cases, rather than to uncover the truth or to achieve justice. This can lead to a situation where lawyers are more concerned with scoring points and attacking the credibility of the opposing side, rather than with presenting a fair and balanced case.

Another problem is that the adversarial system can be heavily skewed towards those who have the resources to mount a vigorous defence or prosecution. The outcome can often be determined by the quality of the legal representation each side is able to secure. This can result in situations where wealthy individuals or corporations are able to hire the best lawyers and thus have an unfair advantage over less affluent individuals or groups.

A further criticism of the system is that it can be adversarial to the point of being hostile and confrontational. This can result in situations where witnesses and victims are treated poorly and where the legal process can be intimidating and traumatic for those involved. This can be particularly true in cases involving sexual assault, domestic violence or child abuse, where victims may be reluctant to come forward or may be subject to aggressive cross-examination.

Whose interests?

Given these flaws, it is worth asking whose interests the adversarial system serves. Critics argue the adversarial system primarily serves the interests of lawyers and the legal profession, rather than the interests of justice or the wider community.

In an adversarial system, lawyers are often able to charge high fees for their services, which can make the legal system prohibitively expensive. This can result in situations where justice is not available to all, but only to those who can afford to pay for it.

In addition, the adversarial system can be seen as serving the interests of those who benefit from the status quo. In many cases, it is used to protect the interests of large corporations or wealthy individuals, who may be able to use their resources to defend themselves against legal challenges. This can result in situations where powerful interests can use the legal system to avoid accountability or to maintain their dominance over others.

The inquisitorial system

Traditionally, the adversarial system is usually contrasted with the inquisitorial system, in which judges are responsible for investigating cases, calling witnesses and gathering evidence.

In England and Wales, we use an inquisitorial system for certain proceedings, the best-known example being the coroner’s inquest. Another is the public inquiry.

But even though inquests and inquiries are formally inquisitorial processes, they are often in reality highly adversarial. The interested persons and his or her lawyers will fight hard to secure the findings they want. Whether a person is represented or unrepresented and how skilled and well-resourced their lawyers are matters a great deal. The difference between an adversarial and an inquisitorial system is not a binary, but a spectrum. Many proceedings have features of both systems.

The same is true when we look at countries outside the common law world. The most famous example of an inquisitorial system is the French criminal justice system, and the numerous other criminal justice systems around the world that are derived from it.

The origins of the French system lie in Napoleon’s 1808 Code of Criminal Instruction. The paradigmatic feature of this tradition is the investigating judge, who oversees the preliminary investigation of the case against the accused.

However, in France today only a small minority of criminal investigations are actually overseen by an investigating judge. Most French criminal investigations are instead overseen by prosecutors, who in the French system are also part of the judiciary. Some other systems that were originally based on the French model have abandoned the investigating judge altogether.

Conversely, the English system has also adopted many features over the past two centuries that would once have been regarded as inquisitorial. At the time when Napoleon laid the foundations of the French inquisitorial system, England and Wales did not have professional police forces or prosecutors, and most criminal cases were brought by the complainant themselves or their relatives.

Professional policing was introduced in all parts of England and Wales by the mid-19th century and in 1879 the post of Director of Public Prosecutions was created. In 1985, the Crown Prosecution Service was set up, creating a full-time corps of professional prosecutors for the first time. The Police and Criminal Evidence Act 1984 codified and extended the powers of the police, giving them power to detain suspects at a police station for questioning. And the traditional paradigm institution of English law, the jury trial, is now used in only a small percentage of all criminal cases.

It’s also the case that Article 6 of the European Convention on Human Rights, which prescribes the minimum standards of a fair trial, has had an impact on both inquisitorial and adversarial systems in Europe.

The court clearly accepts that inquisitorial and adversarial systems can co-exist in Europe and that both can be compliant with Article 6. However, there have been areas where the Article 6 jurisprudence has required changes in inquisitorial systems. For example, the court has taken the view that it is a breach of Article 6 for an investigating judge to sit as a trial judge in the same case. Similarly, although the court accepts that whether to call a witness at trial is a matter for the domestic courts, it has on occasion found a refusal to call defence witnesses to be unfair.

We can see, therefore, that the difference between adversarial and inquisitorial systems is a spectrum rather than a binary. Continental European inquisitorial systems incorporate some elements of adversarial justice, while our own system incorporates some elements that would once have been regarded as inquisitorial. Nonetheless, there are still significant differences between the two systems. ■

Professor Leslie Thomas KC is a lecturer at Gresham College in central London ■

Next week: which is better – adversarial or inquisitorial? And how beneficial is cross-examination?