> Gareth's evidence related to the specific scenarios mentioned in defense, he was not cross examined or asked about other defects : The UK courts rely on the adversarial principle if you don't cross examine, doubt is not considered. The judge could have asked questions, but it is likely they were peeved by the professional discourtesy of not engaging a barrister.
That only applies to a 'fact' witness, not an expert witness.
An expert witness - which is what Gareth Jenkins was presented as - produces a report and submits that report as part of their witness statement.
That report produced by an expert is required to be made on the basis of assisting the court, which means it is supposed to cover things like known issues, caveats, etc. It should have a discussoin about known issues and why they do or do not apply in this instance and so on. An expert witness is required to go far beyond just answering 'the question' like a fact witness would.
And that's the point with respect to Mr. Jenkins, that he was never properly advised of this 'extra' requirements an expert witness needs to perform.
The Duty of an Expert Witness
The duty of an expert witness is to help the court to achieve the overriding objective by giving opinion which is objective and unbiased, in relation to matters within their expertise. This is a duty that is owed to the court and overrides any obligation to the party from whom the expert is receiving instructions - see Criminal Procedure Rules 2020 Part 19. (CrimPR 19.
CrimPR 19.2(3)(d) also obliges all experts to disclose to the party instructing them anything (of which the expert is aware) that might reasonably be thought capable of undermining the expert’s opinion or detracting from their credibility or impartiality.
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3. The expert is impartial
The expert must be able to provide impartial, unbiased, objective evidence on the matters within their field of expertise. This is reinforced by Rule 19.2 of the Criminal Procedure Rules which provides that an expert has an overriding duty to give opinion evidence which is objective and unbiased.
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4. The expert's evidence is reliable
There should be a sufficiently reliable scientific basis for the expert evidence, or it must be part of a body of knowledge or experience which is sufficiently organised or recognised to be accepted as a reliable body of knowledge or experience.
The reliability of the opinion evidence will also take into account the methods used in reaching that opinion, such as validated laboratory techniques and technologies, and whether those processes are recognised as providing a sufficient scientific basis upon which the expert's conclusions can be reached. The expert must provide the court with the necessary scientific criteria against which to judge their conclusions.
In satisfying itself that there is a sufficiently reliable basis for expert evidence to be admitted, the court will be expected to have regard to Criminal Practice Directions 2023 at 7.1.2which states:
"7.1.2Factors which the court may take into account in determining the reliability of expert opinion, and especially of expert scientific opinion, include:
the extent and quality of the data on which the expert’s opinion is based, and the validity of the methods by which they were obtained;
the validity of the methodology employed by the expert;
if the expert’s opinion relies on an inference from any findings, whether the opinion properly explains how safe or unsafe the inference is (whether by reference to statistical significance or in other appropriate terms);
if the expert’s opinion relies on the results of the use of any method (for instance, a test, measurement or survey), whether the opinion takes proper account of matters, such as the degree of precision or margin of uncertainty, affecting the accuracy or reliability of those results;
the extent to which any material upon which the expert's opinion is based has been reviewed by others with relevant expertise (for instance, in peer- reviewed publications), and the views of those others on that material;
the extent to which the expert's opinion is based on material falling outside the expert's own field of expertise;
the completeness of the information which was available to the expert, and whether the expert took account of all relevant information in arriving at the opinion (including information as to the context of any facts to which the opinion relates);
if there is a range of expert opinion on the matter in question, where in the range the expert's own opinion lies and whether the expert's preference has been properly explained; and
whether the expert's methods followed established practice in the field and, if they did not, whether the reason for the divergence has been properly explained.
"7.1.3: In addition, in considering reliability, and especially the reliability of expert scientific opinion, the court must be astute to identify potential flaws in such opinion which detract from its reliability, such as:
being based on a hypothesis which has not been subjected to sufficient scrutiny (including, where appropriate, experimental or other testing), or which has failed to stand up to scrutiny;
being based on an unjustifiable assumption;
being based on flawed data;
relying on an examination, technique, method or process which was not properly carried out or applied, or was not appropriate for use in the particular case; or
relying on an inference or conclusion which has not been properly reached."