IN ANY LEGAL PROCEEDING, the basis on which evidence is collected and presented to a court or other tribunal is of critical importance to the outcome. This column explores the role of expert evidence and compares the position in common law jurisdictions with the position in civil law jurisdictions and mainland China.


This column has previously discussed the adversarial system in common law jurisdictions, where the role of the court is to determine the facts of the dispute on the basis of the submissions made by the parties and as proved by the parties. Unlike the courts in civil law jurisdictions, the common law courts are not inquisitorial in nature; in other words, they do not undertake their own investigations to determine the facts (see, for example, China Business Law Journal volume 7 issue 4: Determining foreign law).

Determining the facts in a legal proceeding can, however, be very difficult. This is particularly so in circumstances that involve complex technical issues. For example, in medical cases where the treatment by a hospital is alleged to have been negligent, the question of whether the hospital’s negligence caused the harm suffered by the patient may be very difficult to answer from a technical perspective. In such circumstances, it is logical to consider the opinion of experts – known as expert witnesses –
to determine issues such as causation.

When a court admits (i.e., allows to be tendered as evidence) the opinion of an expert witness, it recognizes an exception to the general rule of evidence that witnesses should only provide factual evidence and that it is the responsibility of the court – or jury – to determine the conclusions that should be drawn from that evidence. In the case of expert witnesses, the court considers the opinion of a third-party expert to determine critical issues. Although the court is not bound to accept the opinion of the expert witness, particularly where there is conflicting evidence from two or more expert witnesses, the opinion of an expert witness may have significant probative value and may influence – or even determine – the outcome of the case.

In common law jurisdictions, the role of an expert witness is to provide the court with an expert opinion on issues that are relevant to the legal proceeding. Expert witnesses are usually appointed and paid by the parties to the dispute, but they may also be appointed by the court itself. In the situation where the expert witness is appointed by the court, the expert witness has a similar role to an amicus curiae or ‘friend of the court’ (for a discussion about an amicus curiae, see China Business Law Journal volume 10 issue 2: Amicus curiae).

Although the expert witness is usually appointed and paid by the parties to the dispute, the expert witness is not an advocate for a party. Instead, the expert witness has a paramount duty to assist the court and to provide an impartial opinion on matters that fall within the expertise of the witness. In addition, the expert witness must produce an independent report that is not influenced by the appointing party or its lawyers. For example, Order 38, Rule 35A of the Rules of the High Court of Hong Kong provides as follows:

Expert witness’s overriding duty to Court

(1) It is the duty of an expert witness to help the Court on the matters within his expertise.

(2) The duty under paragraph (1) overrides any obligation to the person from whom the expert witness has received instructions or by whom he is paid.

Before a court admits the expert evidence, it must be satisfied that the area of knowledge in which the expert witness has expertise is a recognized body of knowledge that is outside the ordinary human experience. In addition, the court must be satisfied that the expert witness is appropriately qualified to provide the expert opinion.

In most jurisdictions, there are no specific rules or requirements concerning the nature of the qualifications that the expert witness should possess. The essential question is whether the court considers that the expert witness is qualified to provide the opinion. The qualifications of the expert witness may be based on education or experience, or both.

There are many different contexts in which an expert witness may be engaged by one or both parties to provide evidence. These include medical matters, psychological matters that relate to human conduct and the meaning of technical terms. Expert evidence has even been produced to determine the effect of a comma in the interpretation of a termination clause (for a discussion about this context, see China Business Law Journal volume 1 issue 9: Challenges of the language clause).

Expert witnesses are also commonly engaged in matters that require the determination of foreign law. This is because such matters are considered to be a question of fact that are required to be proved by expert evidence (for a discussion about this context, see China Business Law Journal volume 7 issue 4: Determining foreign law).

The Singapore International Commercial Court recognizes an exception to this principle by permitting the parties to an international commercial dispute to make their own submissions on foreign law instead of requiring them to obtain expert evidence (see China Business Law Journal volume 8 issue 10: International Commercial Courts).

The evidence provided by the expert witness is usually contained in a report. In many common law jurisdictions, the rules of the court impose content requirements on the report. These requirements include the following:

    • An acknowledgment that the expert has read the rules concerning expert witnesses and that the opinions of the expert are based wholly or substantially on specialised knowledge arising from the expert’s training, study or experience;
    • The questions that the expert was asked to address; and
    • Copies of the instructions given to the expert by the appointing party and the documents and other materials that the expert was instructed to consider.

In general, it is not possible for an expert witness to claim legal professional privilege in respect of the expert’s own work documents or draft reports (for a discussion about privilege, see China Business Law Journal volume 4 issue 9: Privilege).

As expert witnesses are often appointed by both parties to a dispute, courts (and juries) often have to consider conflicting opinions and determine which opinion is correct. This has led to a practice, originally adopted by Australian courts and subsequently adopted by English courts, where the experts exchange their written reports and meet with each other to prepare a joint statement on the issues that are agreed and the issues that are not agreed. The joint statement then forms the basis for the experts to come together in court (known as “hot tubbing” in English) to give concurrent evidence. Under this procedure, the experts are given an opportunity to discuss the issues with, and answer questions from, each other in court. Although there were some doubts about the benefits and practicalities of this procedure when it was first introduced, it is now generally regarded as an effective and efficient way to identify the key issues in dispute and to clarify the opinions of the experts. This practice is now starting to be used in arbitration proceedings.

In some common law jurisdictions, including Hong Kong, the court can order that expert evidence be provided by a single joint expert. Order 38, Rule 4A of the Rules of the High Court of Hong Kong provides as follows:

Evidence by single joint expert

(1) In any action in which any question for an expert witness arises, the Court may, at or before the trial of the action, order 2 or more parties to the action to appoint a single joint expert witness to give evidence on that question.

(2) Where the parties cannot agree on who should be the joint expert witness, the Court may—

(a) select the expert witness from a list prepared or identified by the parties; or

(b) direct that the expert witness be selected in such manner as the Court may direct.

Where such an order is given, the appointment of a single joint expert witness avoids the risk of conflicting evidence by two or more expert witnesses and also reduces costs and delay.


In civil law jurisdictions, experts are usually appointed by the court and operate under its direction. To ensure the quality and integrity of experts, the courts often maintain official lists of experts. Because experts are appointed by the court, it is necessary to ensure that there is procedural fairness in their appointment and that the experts deliver their reports in a timely manner. As in common law jurisdictions, experts are required to provide impartial, independent and unbiased opinions and are subject to various penalties and sanctions if they fail to do so.

The law in mainland China does not recognize the concept of an expert witness. As this column has previously noted, however, experts have been invited to assist the court in cases involving trademark disputes (for a discussion about this development, see China Business Law Journal volume 10 issue 2: Amicus curiae).

葛安德 Andrew Godwin
Andrew Godwin

A former partner of Linklaters Shanghai, Andrew Godwin teaches law at Melbourne Law School in Australia, where he is an associate director of its Asian Law Centre. Andrew’s new book is a compilation of China Business Law Journal’s popular Lexicon series, entitled China Lexicon: Defining and translating legal terms. The book is published by Vantage Asia and available at