Clark v Ryan
High Court of Australia · 1960
Clark v Ryan (1960) 103 CLR 486
Two vehicles collide on a highway. Does a jury need an expert to tell them what happened?
In the uniform Evidence Acts jurisdictions this common-law test has been displaced. Section 80(b) of the Evidence Act 1995 (Cth) and its State equivalents provide that evidence of an opinion is not inadmissible merely because it is about a matter of common knowledge, removing the limb this case relies on most heavily. Admissibility now runs through s 79: the witness must have specialised knowledge based on training, study or experience, and the opinion must be wholly or substantially based on that knowledge -- the requirements Dasreef v Hawchar applies. Clark v Ryan still states the position at common law and where the uniform Acts do not apply, and the concerns it identifies are what s 79 is addressed to.
What happened?
The case arose from a collision between two motor vehicles on a highway. A witness was called as an expert and gave opinion evidence about how the collision had come about. It was objected to, admitted, and the jury returned a verdict.
What did the Court decide?
The evidence should not have been admitted. Some of it lay outside any qualification the witness could on any generous view be supposed to have; some of it told the jury things the jury was perfectly able to work out for itself. Because the evidence had been objected to and wrongly let in, the verdict was set aside and a new trial ordered.
Proposition
What is the principle?
Opinion evidence from a witness of special skill is admissible only where the subject matter is such that inexperienced people are unlikely to form a correct judgment without assistance, and only from a witness whose profession or course of study gives more opportunity of judging than other people have.
Why does this case matter?
The practical grip of this case is in what it costs. A party with a witness prepared to say something helpful will want to call them, and the fact that the opinion sounds authoritative is exactly what makes it dangerous. Here it was not treated as a slip that could be absorbed: the verdict was set aside and a new trial ordered.
The warning against formulating experience "as a universal law" is aimed at a particular habit — the witness who generalises from what they have seen into a rule, and thereby answers a question nobody was qualified to answer that way.
It is also important to know what has since changed. The common law tests stated here have been overtaken for the uniform Evidence Acts jurisdictions, and one of the limbs discussed in this judgment was deliberately removed by the legislature: under s 80(b) of the Evidence Act 1995 (Cth) and its State equivalents, evidence of an opinion is not inadmissible merely because it is about a matter of common knowledge. The admissibility of expert opinion now runs through s 79, with the Court's modern treatment in Dasreef Pty Ltd v Hawchar.
Exam and application relevance
In a uniform Evidence Acts jurisdiction, start from s 79 and s 80 rather than from this case, and do not argue that an opinion is inadmissible because it concerns a matter of common knowledge — s 80(b) has removed that ground. What survives is the requirement of specialised knowledge based on training, study or experience, and that the opinion be wholly or substantially based on it; check the scope opinion by opinion, because a witness qualified on one matter may stray into another. At common law, and where the uniform Acts do not apply, the two questions this case separates are still the right ones to ask.
Check your understanding
The witness had real experience with vehicles. Why was that not enough to make his opinion admissible?