The problems associated with expert witness
It is often said that the principal danger of adversary expertise is
“motivational bias”. As expert witnesses are employed by one of the
parties to the litigation and they would purposely mould their views to fit
their client’s proceedings. In fact, the problem of lack of objectivity in
expert evidence is not a new phenomenon. As early as in Lord Abinger v.
Ashton, Sir George Jessel said: “Undoubtedly there is a natural bias to do
something serviceable for those who employ you and adequately
remunerate you,” and expert witness may even considered themselves as
the “paid agents” of their employers. The problem of adversarial bias is
also “widespread” in Hong Kong. As identified in the Interim Report of the
Working Party on Civil Justice Reform, a major problem concerning expert
evidence is the partisanship and lack of independence among experts.
Thus, it is suggested by Professor Gary Edmond that partisanship may be
“an unavoidable feature of knowledge production and expert opinion”.
Another reason for lack of objective expert evidence is due to the problem
of “expert shopping”, which is a process of selecting opinions from one
expert after another, until the most favourable opinion to the party’s case
is found. Since the choice of experts lies with the parties, the expert
evidence is selected on the basis that would serve the best interests of
their client’s cases. Consequently the court does not necessarily obtain
the most independent or objective expert evidence. The practice of
selecting the “most favorable expert” is indeed a distortion of the
rationale behind expert evidence as well as a discredit to the
administration of justice.
2.1 The duties of expert witness
Due to the concern about the failure of experts to provide an independent
and objective opinion, a developed code of conduct has been set out in
National Justice Compania Naviera SA v. Prudential Assurance Co. Ltd.
(The Ikarian Reefer) to clarify the duties of an expert witness. The most
important parts are the first two numbered paragraphs, which stated that:
“1) Expert evidence presented to the Court should be the independent
product of the expert uninfluenced as to form or content by the exigencies
of litigation; 2) An expert witness should provide independent assistance
to the Court by way of objective unbiased opinion in relation to matters
within his expertise.” The Ikarian Reefer guidelines remain a good law in
Hong Kong, and the relevant principles were set out in paragraph L1/58/7
of Hong Kong Civil Procedure 2009. The expert witness’s “overriding duty”
to provide independent and unbiased assistance to court is also reflected
in Order 38, rule 35A of the Rules of the High Court (RHC) as well as the
Code of Conduct for Expert Witness in Appendix D of RHC. Further
guidance is provided in Hong Kong Air Cargo Terminals Ltd. v.
Commissioner of Rating and Valuation that an expert also needs to ensure
no omission of material facts that could divert from his concluded opinion.
, Although the adversary system may not have provided an ideal
environment for the expert witnesses to maintain their independence and
objectivity from their clients, I believed that the promulgation of code of
conduct would have raised awareness of the expert witnesses in meeting
the court’s expectations, so that they will be less easily manipulated by
lawyers, which can tend to rein in the “widespread” problem of expert
bias in Hong Kong.
Court-appointed experts
Apart from a code of conduct for expert witnesses, some commentators
have recommended other ways to reduce the problem of expert bias, and
one of them is the appointment of court experts with reference to the
inquisitorial system. It is common for the court to appoint experts in many
continental jurisdictions, such as Belgium, Germany and France. Unlike
the way to appoint experts under the adversarial system, the expert
witnesses are selected and remunerated by an independent authority,
usually the court rather than the parties, which may avoid the problem of
adversarial bias. Take an example of the French system of expertise, the
judge would normally commission the expert witnesses from a list of
official experts, and they will be questioned by the judge. The major
distinction between the adversarial and inquisitorial system of justice is
that the parties play a minimal role in locating evidence and they need
not actively engage with the expert witness in court, as the expert witness
is infrequently cross-examined by the defendants. As the court-appointed
expert has little interaction with the parties, they are more likely to give
an objective and unbiased opinion to the Court.
Nevertheless, it is argued that the appointment of court experts under the
inquisitorial system is contrary to the principles of the adversarial system
of justice. Apart from the loss of right for parties to select their own expert
witnesses, there are a number of arguments that go against the
inquisitorial court-appointed experts. First of all, the main problem is that
the court may place “undue reliance” on the evidence provided by the
court-appointed expert, which may lead to an ultimate result that it would
be the court-appointed expert instead of the judge who decides the
case. This is also highlighted by Lord Denning in In re Saxton that the
appointment of a court expert in England is a “rare thing”, as “the
litigants realize that the court would attach great weight to the report of a
court expert, and are reluctant to leave the decision of the case so much
in his hands.”
Second, it is difficult to ensure the validity or test the applicability of the
expert evidence in inquisitorial systems due to lack of cross-examination
and involvement of more expert opinion, which are fundamental features
of the adversarial system. In the absence of challenges to expert
evidence, its quality and reliability is therefore doubtful as there is no way
to test the correctness of the expert conclusion. Moreover, the exercise of
court’s power to appoint an expert is rare under Order 40 of RHC in Hong
Kong. It is indicated in the case of Nguyen Ho & Others v. Director of
It is often said that the principal danger of adversary expertise is
“motivational bias”. As expert witnesses are employed by one of the
parties to the litigation and they would purposely mould their views to fit
their client’s proceedings. In fact, the problem of lack of objectivity in
expert evidence is not a new phenomenon. As early as in Lord Abinger v.
Ashton, Sir George Jessel said: “Undoubtedly there is a natural bias to do
something serviceable for those who employ you and adequately
remunerate you,” and expert witness may even considered themselves as
the “paid agents” of their employers. The problem of adversarial bias is
also “widespread” in Hong Kong. As identified in the Interim Report of the
Working Party on Civil Justice Reform, a major problem concerning expert
evidence is the partisanship and lack of independence among experts.
Thus, it is suggested by Professor Gary Edmond that partisanship may be
“an unavoidable feature of knowledge production and expert opinion”.
Another reason for lack of objective expert evidence is due to the problem
of “expert shopping”, which is a process of selecting opinions from one
expert after another, until the most favourable opinion to the party’s case
is found. Since the choice of experts lies with the parties, the expert
evidence is selected on the basis that would serve the best interests of
their client’s cases. Consequently the court does not necessarily obtain
the most independent or objective expert evidence. The practice of
selecting the “most favorable expert” is indeed a distortion of the
rationale behind expert evidence as well as a discredit to the
administration of justice.
2.1 The duties of expert witness
Due to the concern about the failure of experts to provide an independent
and objective opinion, a developed code of conduct has been set out in
National Justice Compania Naviera SA v. Prudential Assurance Co. Ltd.
(The Ikarian Reefer) to clarify the duties of an expert witness. The most
important parts are the first two numbered paragraphs, which stated that:
“1) Expert evidence presented to the Court should be the independent
product of the expert uninfluenced as to form or content by the exigencies
of litigation; 2) An expert witness should provide independent assistance
to the Court by way of objective unbiased opinion in relation to matters
within his expertise.” The Ikarian Reefer guidelines remain a good law in
Hong Kong, and the relevant principles were set out in paragraph L1/58/7
of Hong Kong Civil Procedure 2009. The expert witness’s “overriding duty”
to provide independent and unbiased assistance to court is also reflected
in Order 38, rule 35A of the Rules of the High Court (RHC) as well as the
Code of Conduct for Expert Witness in Appendix D of RHC. Further
guidance is provided in Hong Kong Air Cargo Terminals Ltd. v.
Commissioner of Rating and Valuation that an expert also needs to ensure
no omission of material facts that could divert from his concluded opinion.
, Although the adversary system may not have provided an ideal
environment for the expert witnesses to maintain their independence and
objectivity from their clients, I believed that the promulgation of code of
conduct would have raised awareness of the expert witnesses in meeting
the court’s expectations, so that they will be less easily manipulated by
lawyers, which can tend to rein in the “widespread” problem of expert
bias in Hong Kong.
Court-appointed experts
Apart from a code of conduct for expert witnesses, some commentators
have recommended other ways to reduce the problem of expert bias, and
one of them is the appointment of court experts with reference to the
inquisitorial system. It is common for the court to appoint experts in many
continental jurisdictions, such as Belgium, Germany and France. Unlike
the way to appoint experts under the adversarial system, the expert
witnesses are selected and remunerated by an independent authority,
usually the court rather than the parties, which may avoid the problem of
adversarial bias. Take an example of the French system of expertise, the
judge would normally commission the expert witnesses from a list of
official experts, and they will be questioned by the judge. The major
distinction between the adversarial and inquisitorial system of justice is
that the parties play a minimal role in locating evidence and they need
not actively engage with the expert witness in court, as the expert witness
is infrequently cross-examined by the defendants. As the court-appointed
expert has little interaction with the parties, they are more likely to give
an objective and unbiased opinion to the Court.
Nevertheless, it is argued that the appointment of court experts under the
inquisitorial system is contrary to the principles of the adversarial system
of justice. Apart from the loss of right for parties to select their own expert
witnesses, there are a number of arguments that go against the
inquisitorial court-appointed experts. First of all, the main problem is that
the court may place “undue reliance” on the evidence provided by the
court-appointed expert, which may lead to an ultimate result that it would
be the court-appointed expert instead of the judge who decides the
case. This is also highlighted by Lord Denning in In re Saxton that the
appointment of a court expert in England is a “rare thing”, as “the
litigants realize that the court would attach great weight to the report of a
court expert, and are reluctant to leave the decision of the case so much
in his hands.”
Second, it is difficult to ensure the validity or test the applicability of the
expert evidence in inquisitorial systems due to lack of cross-examination
and involvement of more expert opinion, which are fundamental features
of the adversarial system. In the absence of challenges to expert
evidence, its quality and reliability is therefore doubtful as there is no way
to test the correctness of the expert conclusion. Moreover, the exercise of
court’s power to appoint an expert is rare under Order 40 of RHC in Hong
Kong. It is indicated in the case of Nguyen Ho & Others v. Director of
