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Evidence Opinion And Expert Evidence Notes

BCL Law Notes > Evidence I: Foundations Notes

This is an extract of our Evidence Opinion And Expert Evidence document, which we sell as part of our Evidence I: Foundations Notes collection written by the top tier of University College Dublin students.

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The opinion evidence rule - opinion evidence is inadmissible
An opinion is an inference that a person draws from facts
There's a general rule that ordinary people cannot give opinion evidence.
Judge should ideally

1. Stop them before they finish

2. Declare it inadmissible

Common sense and common fat - no more qualified than anyone else
It is not for the WITNESS to answer the 'final question' - this is the role of the judge or jury.
However - juries are giving opinions too - they are not obliged to take the opinion - they can make their own decision on that opinion of the lay person giving evidence
We don't trust juries.
Also don't wanna waste time on opinions of witnesses•


When there are facts that are too complex for an ordinary judge or juror to interpret without some expert assistance
They are merely there to aid the judge, with their expert opinion, to understand what is going on.
The whole purpose of them as a witness is merely because of their opinion and to give it

Recently - expert evidence becoming very common in criminal trials - why?Reaction to discovery that many traditional forms of evidence are less reliable than was formerly thought?
Identification evidence, confession evidence.

Galvin v Murray 2001
Murphy j'In general terms, an expert may be defined as a person whose qualifications or expertise give an added authority to opinions or statements given or made by him within the area of his expertise.' Criminal Procedure Act 2010Section 34(9) "a person who appears to the court to possess the appropriate qualifications or experience about the matter to which the expert's evidence relates".

Mr Justice O'Flaherty: (writing extra-judicially) 'the person must be properly qualified in the field in which he says he is qualified. To put it colloquially: he must know his stuff'.

However, doesn't necessarily mean they have to have a degree or written documental qualification.

Always open to challenge and then a voire dire will be directed

2008 LRC - consultation didn't include the need for a qualification a) Personal experience could qualify them b) Could be such a niche area that it isn't of studies yet.
c) Area can also be very new - formal qualifications simply don't exist
R v Silvercock 1894
Semi-professional - no qualifications. A solicitor who had studied handwriting in an amateur capacity for 10 years was allowed give evidence as an expert witness.Allowed act as a witness and gave opinion evidence

People v Howe 2003
Forensic scientists held not to be qualified to give statistical evidence on the probability of identical
DNA coming from another person. When a DNA scientist declares a match - they must give a statistical analysis in terms of the amount of people with the DNA sample marker.As the scientist had no qualifications in the area of statistics.

Differed from Silvercock.
People DPP v Boyce 2005
DPP v Connelly 2011

'fraught risk of unfairness'

Haines v Bellissimo - Canada
Griffin JPsychology and psychiatry are inexact sciencesAccepted but less bound to accept as being 'infallible'

Fennell no.1 1940
Two psychologists giving opinion that the accused was insane. Number of witnesses non eperts at scene - give evidence that he was acting rationally and normally at the time of the murderCourt placed more weight on the witness evidence than on expert opinionJuries not bound to follow opinion of the experts -

There will usually be two experts - one on both sides

Jury makes a decision or can disregard it completely

If an expert opinion was binding, it would become trial by expert and not trial by jury


1. When the court has to deal with a matter outside the ordinary knowledge of the jury

2. When witness possesses specialised knowledge that may assists the jury in reaching verdict.

AG (Ruddy) v. Kenny (1960) 94 ILTR 185
Majority held that drunkenness was something that any ordinary person would be qualified to provide opinion evidence and added that a Garda was "specifically qualified" to judge this.Witnesses can give an opinion that is deemed something that the layperson can give opinion on

People (DPP) v. Pringle (1981) 2 Frewen 57 Appellant - the expert evidence was unnecessary - he was convicted on the basis of clothing fibre analysis, they took a fibre from clothing and it matched that of the crime scene. Expert was brought in to confirm this. The accused said that there was no need for an expert - the ordinary person could have looked at a fibre and compared them.UnsuccessfulNot as easy as made outDeemed something that an ordinary person could give opinion onWe don't want to share around microscopes to judges and juries- it is not procedure we want to follow.

Unsuccessful argument that expert evidence was unnecessary and should not have been used.
Courts have made use of expertise from wide range of fields of expertise.
Galvin v. Murray [2001] 2 I.L.R.M. 234
Murray J: 'an expert may be defined as a person whose qualifications or expertise give an added authority to opinions or statements given or made by him within the area of his expertise.'
Categories have never been limited.

Legal experts? Expert evidence is not necessary and therefore is not admissible in respect of any matter of domestic law.Judges are meant to be experts of law

But see McMullen v. Farrell [1993] 1 I.R. 123Allowed solicitor to give expert opinion on normal practice in a solicitor's professionWe cannot assume that barrister and lawyer and judge are conversiveJudge not necessarily a solicitor to become a judge

5. Proof of Foreign LawIt is strictly against the rules for a domestic judge to give opinion or try to interpret foreign law.Expert evidence is required here.

What is Irish law and what is foreign law?

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