R v Gardner & Coates [2003] VSC 153

Supreme Court of Victoria|2003-05-21|Before: SMITH J

A ruling is sought as to the admissibility of DNA evidence sought to be led by the Crown.

The Crown wishes to lead evidence from Ms Brown, a forensic scientist, as to the results of DNA testing of biological material found on a green baseball cap which in turn was found in the laneway used by the alleged armed robbers to go from one getaway car to another.

The Crown wishes to lead the following evidence:

(a) (i) the DNA testing was inconclusive as to whether Gardner could be excluded as a source of the biological material but indicated that he could have contributed to it;

(ii) Coates could not be excluded as a contributor to the material;

(b) (i) that the DNA typing obtained would be 63 times more likely if it had come from Coates and one unknown individuals than if it had come from 2 unknown individuals chosen at random from the Victorian Caucasian population; (ii) that that finding considered in isolation provided moderate support for the proposition that the biological material originated from Coates and one unknown randomly selected individual from the Victorian Caucasian population.

I note that this particular finding involved effectively consideration of the results of four of the nine examinable areas.

Both the Crown and Coates asked Ms Brown to do a number of statistical analyses of different hypothetical combinations which included Gardner. I was informed by counsel for the Crown that Ms Brown had concerns about the scientific validity of the hypothetical comparisons and wished to do no more, in any evidence in chief, than provide the above statistical comparison between the hypothesis of Coates and one unknown individual as contributors on the one hand and 2 unknown individuals on the other as the sources of the biological materials. Counsel informed the court that Ms Brown was reluctant to advance statistical evaluations of hypothetical combinations including Gardner because the information available left the issue of exclusion inconclusive -- that is unlike Coates, there was apparently insufficient evidence to be able to say that he could not be excluded. The difficulty apparently arises from the area known as vWA where there were indications consistent with Gardner being a contributor but insufficient to cross the threshold required to permit them to be used. Apparently a possible explanation for this was an absence of sufficient material. In that area there were indications of a possible 16 which was consistent with Gardner but also of a 14 which was not. Neither, however, was reportable and Ms Brown treated that area examination as inconclusive.

Before turning to the submissions, I note that it is common ground that the DNA evidence establishes that there must have been two contributors to the biological material and that three contributors cannot be excluded. If, however, there were only two contributors, they could not comprise the two accused because there were findings made at two areas which matched neither accused. Thus if only two people supplied the biological material, it could be only Coates and one unknown person or Gardner and one unknown person.

Counsel for the Crown submitted that the baseball cap was an item found at a secondary crime scene, close to the red utility that was set on fire and on the path taken by the alleged armed robbers between the two alleged getaway cars. The Crown submitted that the evidence would be relevant if a connection can be established between the baseball cap and one of the robbers. Counsel submitted that the fact that the DNA material found linked the baseball cap to the accused Coates was relevant probative and admissible. Counsel submitted that the inference would be open that the person fleeing the scene left the baseball cap behind, that the person who had the cap was connected to the crime and that person was Coates.

Thus the Crown relies on the DNA evidence to connect Coates to the armed robbery. But it can only do that if the DNA evidence alone, or in combination with other evidence, is capable of giving rise to the inference that Coates left the cap behind in the laneway during the robber's flight.

Evidence may be said to be relevant where, if accepted, it could rationally affect, directly or indirectly, the assessment of the probability of the existence of a fact in issue. Determining relevance, however, is not simply a matter of logic. The common law requires that evidence be of sufficient relevance[1] before it is admissible. Here the issue arises in a particular context. The evidence of the baseball cap, and its location, and the DNA evidence, is said by the Crown to be relevant because, in combination, it can give rise to the inference that Coates left the baseball cap in the laneway while escaping after the robbery.

Counsel for Coates submitted that the evidence has no probative value and is therefore irrelevant and inadmissible. In the alternative, it is put that if there is any probative value it is very slight and the prejudicial effect of the evidence will outweigh any probative value.

Plainly the points in issue in the case need to be identified and the probative value, if any, to those issues that the DNA evidence may have needs to be determined.

There is no issue as to the involvement of Gardner in the armed robbery or his presence in the laneway at the relevant time. There is, however, an issue as to the involvement of Coates in the armed robbery and his presence in the laneway at the relevant time. The baseball cap has the potential to link Coates to the armed robbery if there is evidence from which it would be open to find, in conjunction with other evidence if necessary, that he left the baseball cap in the laneway at the relevant time.

If the situation was that the DNA found on the baseball cap could be connected only to Coates and no one else, an inference would be open that he had left his baseball cap in the laneway some time not long before the police inspection and that he was, therefore, one of the alleged robbers. But that is not this case.

The DNA evidence set out in paragraph 3 (a) above, if accepted, establishes that biological material was found on the internal head band of the baseball cap and that Coates, as a source, could not be excluded. But, as counsel for Coates submitted, the DNA evidence, if accepted, also establishes that Gardner could have contributed to it and his exclusion was equivocal -- in other words it is unclear whether he cannot be excluded as a source of the DNA. It is put that, therefore, the jury cannot assume, as counsel submitted the Crown had in fact done, that the baseball cap was not connected to Gardner at the relevant time.

As to this aspect of the DNA evidence, it does not itself provide a basis upon which a conclusion, preliminary or otherwise, could be drawn connecting the baseball cap to Coates to the exclusion of Gardner. There is no other evidence foreshadowed by the Crown that would enable a jury to make a choice excluding Gardner as the wearer or carrier of the baseball cap. The evidence cannot have probative value in relation to the critical issue of Coates involvement unless there is evidence which, if accepted, could exclude Gardner.

The Crown faces other problems. First, the DNA testing points to a third person having contact with the baseball cap. Secondly, the DNA evidence cannot itself provide evidence as to the time when the biological material was deposited on the baseball cap. There being more than one potential source of DNA, there needs to be some evidence on which it would be open to find that the DNA material that can be connected to Coates was placed by him on the baseball cap shortly prior to it being left in the laneway before the necessary inferences could be drawn. There does not, however, appear to be any evidence on which it would be open to reach such a conclusion . In addition, other apparently undisputed evidence will show the existence of a friendship and association between the accused, including the use by Gardner of Coates' home and material from it. Thus, undisputed evidence exists which will support the possibility that Gardner had borrowed the baseball cap from Coates - assuming that it belonged to Coates and not the third person or Gardner.

One of the hypotheticals tested by Ms Brown compared the likelihood that the material was deposited by Coates and one unknown person rather than Gardner and one unknown person. Comparing information obtained from three areas only, Ms Brown has calculated that the former is ten times more likely. Ms Brown, however, is concerned about the statistical validity of comparisons of hypotheses involving Gardner and the Crown does not rely upon it.

I have considered whether the proposed evidence might be relevant, when considered with the other evidence, on the basis that it could give rise to the inference that Coates was an active participant in the robbery. In my view, again, the foreshadowed evidence could not do so.

I turn to the evidence (above 3 (b)) as to the likelihood of the DNA having been contributed by Coates and an unknown person as compared to two unknown persons. I can see no basis for saying that this evidence is relevant to the actual issues in the case. If it was to be assumed that that evidence proved beyond reasonable doubt that Coates supplied the material as opposed to unknown persons, it does not address, directly or indirectly the real issue in the case which is whether Coates, as opposed to Gardner, left the baseball cap behind in the laneway.

Counsel for Coates also submitted that if there be some probative potential, and therefore relevance, the evidence should be excluded because of its prejudicial effect which counsel submitted would outweigh any probative value. Counsel submitted that it would be impossible to explain in any clear way to the jury how to deal with the DNA evidence itself and the conclusions to be drawn from it. Counsel for the Crown, however, submitted that while evidence of DNA and the related statistics is difficult it would be possible to present it to a jury in an understandable way so that there would be no risk of misuse of the evidence or misestimation of its weight by the jury to the unfair prejudice of the accused Coates.

In my view there is considerable potential for the evidence to be misused or given too much weight. It is difficult, if not impossible, without proper grounding in the statistical analysis of DNA, to form a view as to the significance of the probative difference between the statements that the findings had the result that Coates could not be excluded as a contributor to the biological material whereas Gardner could have been a contributor but it was unclear whether he could not be excluded as a contributor. [2]

In the typical circumstantial case, the jury can call on its collective commonsense and experience to assess the combined impact of the circumstances it considers. Commonsense and experience will not assist the jury in assessing and comparing the DNA evidence - both the general opinions and the specific conclusions such as

"63 times more likely", or "10 times more likely". Counsel have not been able to suggest to me how the jury might be assisted in the task of determining how much weight to attach to such conclusions in a way relevant to resolving the question whether the Crown has proved its case beyond reasonable doubt. I have not been referred to any simple formula or analogies that might be used to understand the weight of this evidence.

For the foregoing reasons, it appears to me that, if either aspect of the evidence has relevance, it should be excluded in the exercise of the discretion because of the risk of prejudice flowing from mis-estimation of the weight of this evidence.

[2] For recent discussion see Andrew Ligertwood "Avoiding Bayes in DNA Cases" (2003) 77 ALJ. The statistical information is not presented in the form of relative frequency but rather in the form of a likelihood ratio.

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