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Fitzgerald v R [1] is both familiar to the legal and scientific communities and presents a poignant example of the weight a jury may apply to prejudicial elements of unchallenged scientific evidence.

The Fitzgerald conviction as recounted in the High Court appeal judgement, relied upon valid modern day DNA science presented to the jury alongside scientific expert opinion in the absence of supporting data.

An opinion is an inference drawn from observed and communicable data. [2]

Through this discussion paper, I will dissect the subtleties of the DNA evidence within the judgement and demonstrate that the outcome is as equally possible in today’s courtroom, as it was in 2014.

In this matter, the expert evidence at hearing delivered verbal weightings such as “more likely”, “much more likely” and “most likely”, when speaking to critical aspects of the scientific evidence.

Significantly, these weightings countered the substantive fundamental basis of acknowledged scientific theory at hearing. Such unsupported weightings should firstly not be presented in DNA expert evidence, secondly should be challenged, and thirdly should be rejected by the courts when they are proffered.

It is, and correctly should be, the case that DNA expert opinion before the court is more than mere scientific conjecture.

Makita (Australia) Pty Ltd v Sprowles set out the role of an expert witness;

 “Their duty is to furnish the Judge or jury with the necessary scientific criteria for testing the accuracy of their conclusions, so as to enable the Judge or jury to form their own independent judgment by the application of these criteria to the facts proved in evidence. The scientific opinion evidence, if intelligible, convincing and tested, becomes a factor (and often an important factor) for consideration along with the whole other evidence in the case, but the decision is for the Judge or jury.“[3]

My experience is that unsupported expert opinions are frequently tendered orally, when those opinions have in fact not been made out in the filed expert written testimony.

Oral expert weightings can be highly persuasive to a jury.

In Fitzgerald, it seems the Court of Criminal Appeal was similarly persuaded by oral expert weightings when unanimously rejecting the appeal;

 ‘in light of Dr Henry’s evidence, the alternative hypothesis of a secondary transfer of the appellant’s DNA to the didgeridoo by Sumner was “extremely unlikely“’. [1]

The inclination may be to assign responsibility for such errors to either scientific evidence or the legal system, I propose that the failures lie largely in the somewhat undisturbed void between the two.

In compiling this assessment, the High Court Judgement has been relied upon as factually accurate. It should fairly be acknowledged, that statements within the judgement purporting to be made by the crown expert, may have been interpreted, transcribed without sufficient precision, or taken out of context within the judgement.

Fitzgerald v The Queen [2014] HCA 28 (13 August 2014)

For those unfamiliar, it was alleged that Mr Fitzgerald did enter a dwelling in company, at which time a series of assaults occurred, resulting in the death of one man, and significant injury to another. Mr Fitzgerald and Mr Sumner were found guilty and sentenced to life.

The prosecution sought to rely on DNA evidence and the appearance of blood, which was identified upon a didgeridoo that was normally within the dwelling. It was alleged, that in light of this evidence, the accused had deposited his DNA directly on the didgeridoo whilst attending the dwelling during the assault. The prosecution relied significantly upon DNA expert witness testimony.

The defence version set out that Mr Fitzgerald did not participate in the assault, nor attend the residence, and rather his DNA came to be on the didgeridoo as a result of shaking Mr Sumners hand the night prior, with Mr Sumner subsequently and unintentionally transferred the DNA into the crime scene. The defence did not rely on a DNA expert at hearing.

The evidence concerning DNA

HCA 28 – para 12 ‘The appellant was excluded from DNA results taken from a variety of objects found at the crime scene and from four out of five forensic samples taken from the didgeridoo. However, one forensic sample from the didgeridoo, Sample 3B, contained a mixed DNA profile of “major” and “minor” contributors. The appellant’s DNA was the major contributor and an unknown source was the minor contributor’.

Helen Roebuck – Defining a major contributor is a subjective assessment.

A major contributor is considered to have contributed a greater quantity of DNA as compared to the minor contributor. It does not necessarily mean that there is a large DNA quantity, in fact there may very well not be.

The scientifically accepted theory in this regard has not substantially changed since 2014.

Sample 3B

 HCA 28 – para 18 ‘That the appellant’s DNA was contained in Sample 3B was not challenged by the appellant’.

Helen Roebuck – Veracity of the DNA match should always be considered. Number of contributors assigned, ethnic database selection, anti- contamination procedures, sample contamination checks, robustness of the match and probabilistic genotyping diagnostics review are some of the matters for consideration in this process. The scientifically accepted theory in this regard has not substantially changed since 2014.

HCA 28 – para 19  ‘A qualified forensic expert, Dr Julianne Henry, gave evidence at the trial for the prosecution. She explained that Sample 3B came from an area on the didgeridoo showing “reddy-brown stains” which had been removed using a scalpel. The sample consisted of two separate “bloodlike stains”, one having a diameter of 2 millimetres by 1 millimetre and the other a diameter of less than 1 millimetre. Dr Henry said that even if the abovementioned “reddy-brown stains” were in fact blood (as indicated by a presumptive test), that circumstance did not prove that the DNA in Sample 3B derived from blood because the DNA may have been “under the stain”, i.e. placed on the didgeridoo at an earlier time. She agreed with counsel for the prosecution that the “reddy-brown stains” may have “contributed nothing” to Sample 3B’.

Helen Roebuck – Confirmatory testing is required to establish with certainty that blood is present. Small quantities may not be sufficient to conduct anything more than presumptive testing. It is stated that the DNA may have been “under the stain”. Indeed, the DNA may have alternatively been “on top of the stain”, as the scientific evidence does not preclude this scenario. The order of deposition can be significant. The scientifically accepted theory in this regard has not substantially changed since 2014.

DNA and blood

HCA 28 – para 20 ‘Dr Henry explained that DNA, a molecule in cells from the human body, can be transferred to an object in biological fluid such as blood (or saliva) or through contact with a person’s skin. She said the amount of DNA transferred through contact with a person’s skin, called “contact” or “trace” DNA, is low compared to the amount of DNA transferred in a biological fluid. Finally, Dr Henry gave evidence that some people “shed” contact or trace DNA more readily than others’.

Helen Roebuck – Empirical studies have shown that the amount of DNA obtained from transferred through touch can indeed equal or exceed that present in a small bloodstain (ie 2mm x 1mm as at 19 above). The scientifically accepted theory in this regard has not substantially changed since 2014.

HCA 28 – para 21 ‘Dr Henry stated that there were three possible ways in which blood may be transferred to an object: direct transfer (where contact occurs between a person and an object), airborne transfer (where blood travels through the air and then lands on an object) and passive transfer (where a person’s blood drips onto an object). Dr Henry was unable to distinguish, from a photograph, whether the deceased’s blood on the didgeridoo was transferred directly or by having been airborne’.

Helen Roebuck – Bloodstain pattern analysis is a discrete area of experience and expertise. Assessment is generally conducted using high resolution photographs. The point above states that the expert was unable to distinguish from a photograph. It is unclear if there was or was not a photograph, and if there was a photograph, whether there was a quality issue, or in fact the expert was inferring that a photograph is generally unsuitable to conduct Bloodstain Pattern Analysis. Should there have been a photograph of sufficient quality, it is likely that further information could have been gleaned that would provide assistance in regard to method of deposition. The scientifically accepted theory in this regard has not substantially changed since 2014.

Primary and secondary DNA transfer

HCA 28 – para 22 ‘Dr Henry explained the differences between “primary” and “secondary” DNA transfer. A primary transfer occurs as a result of direct contact between a particular person and an object. A secondary transfer occurs when contact or trace DNA is transferred onto an object by an intermediary as a result, for example, of a handshake. Dr Henry gave evidence that the most likely way to obtain contact or trace DNA on an object was through primary, rather than secondary, transfer’.

Helen Roebuck – A statement that “the most likely way to obtain contact or trace DNA on an object was through primary, rather than secondary, transfer” is scientifically invalid, in the absence of supporting data. The scientifically accepted theory in this regard has not substantially changed since 2014.

HCA 28 – para 22  ‘She [Dr Henry] also stated that a secondary transfer of DNA remains possible a few hours after contact between a person and an intermediary, and that an intermediary’s DNA is not necessarily transferred at the same time, although she was only aware of one example of this in the relevant literature. She accepted as a possibility that the appellant’s DNA in Sample 3B was the result of a secondary transfer’.

Helen Roebuck – The statement that “secondary transfer of DNA remains possible a few hours after contact between a person and an intermediary”, infers that transfer beyond a few hours is not possible. If this inference is intended, it is scientifically invalid. The scientifically accepted theory in this regard has not substantially changed since 2014.

Mixed DNA profiles

HCA 28 – para 23 ‘Dr Henry explained that where DNA of more than one person is identified in a sample, there will usually be one major contributor and one minor contributor to the DNA profile. In most (but not all) cases where a secondary transfer of DNA occurs, the major contributor to the DNA profile will likely be the person transferring the DNA and the minor contributor will be the person whose DNA is transferred’.

Helen Roebuck – In my opinion, the statement “In most (but not all) cases where a secondary transfer of DNA occurs, the major contributor to the DNA profile will likely be the person transferring the DNA and the minor contributor will be the person whose DNA is transferred” is misleading of the court. The scientifically accepted theory in this regard has not substantially changed since 2014.

HCA 28 – para 23 ‘Dr Henry gave evidence that it was likely that a person who was the major contributor to a DNA profile would have left blood on an object because blood is a richer source of DNA than epithelial cells’.

Helen Roebuck– In my opinion, the statement “it was likely that a person who was the major contributor to a DNA profile would have left blood on an object because blood is a richer source of DNA than epithelial cells” is misleading of the court.It is relevant to mention that this statement was at least partially corrected under cross examination as noted below.The scientifically accepted theory in this regard has not substantially changed since 2014.

HCA 28 – para 23 ‘However, she [Dr Henry] went on to state that it was possible that the DNA in Sample 3B was derived from a source other than blood because “it was difficult to conclude from the yield of DNA that we obtained from those stains that the DNA did come from blood”. After giving that evidence, she was cross-examined about the source of the DNA in Sample 3B. It is convenient to set out the passage transcribing her answers’:

A. ‘It could have been blood, it could have been something other than blood’.

     Helen Roebuck – Agreed

17. ‘By ‘something else’ it could be saliva for example’.
18. ‘That’s possible, yes’.

Helen Roebuck – It could have been saliva yes. Significantly, the positive presumptive test, could have in fact been the result of a non- biological material. For example, oxide based paint, rust, metallic traces or certain cleaning products, amongst other things. The scientifically accepted theory in this regard has not substantially changed since 2014.

17. ‘It could be the transference of cells’.
18. ‘That’s possible, yes’.

Helen Roebuck – Agreed

17. ‘And we will come back to the question of transfer, but primary or secondary transfer’.
18. ‘Yes’.

Helen Roebuck – Agreed (except that secondary transfer is correctly indirect transfer).

HCA 28 – para 24 ‘Sumner’s DNA was not found on the didgeridoo at all. That was relevant to the appellant’s reliance upon an hypothesis of a transfer of DNA from the appellant’s hand to Sumner’s hand when the two men shook hands at the boxing match, and a subsequent secondary transfer of the appellant’s DNA to the didgeridoo by Sumner on one or other of his two visits to the house on 19 June 2011’.

Helen Roebuck – It is apparent that no review of the DNA profile was conducted. Mixed DNA profiles can be highly complex and exclusion of an individual can be subjective. The scientifically accepted theory in this regard has not substantially changed since 2014.

DNA accumulation

HCA 28 – para 25 ‘Dr Henry stated that recovering DNA from an object does not indicate the time of its deposit on the object from which it is retrieved. With current technology, DNA cannot be “aged”. She also stated that DNA could accumulate over a period of time, days or even weeks, and she accepted that contact or trace DNA could have been on the didgeridoo for some time before the attack’.

Helen Roebuck – Agreed

The reasoning of the Court of Criminal Appeal

HCA 28 – para 26 ‘The Court of Criminal Appeal (Gray and Sulan JJ; Blue J agreeing) found that it was open to the jury to conclude beyond reasonable doubt that the appellant’s DNA was deposited on the didgeridoo as a result of direct contact by the appellant at the time of the attack. In their Honours’ view, in light of Dr Henry’s evidence, the alternative hypothesis of a secondary transfer of the appellant’s DNA to the didgeridoo by Sumner was “extremely unlikely”. In so concluding, the Court of Criminal Appeal confined its considerations to Sumner’s second visit to the house at around 6:00am and did not refer to Dr Henry’s evidence that an intermediary’s DNA will not necessarily be deposited when the intermediary makes a secondary transfer of another’s DNA. Further, the Court of Criminal Appeal referred neither to the possibility that the appellant’s DNA may have been the subject of a primary transfer to the didgeridoo on an occasion earlier than the attack nor to Dr Henry’s evidence about the accumulation of DNA and the impossibility of “dating” DNA. The Court of Criminal Appeal concluded that the jury was entitled to reject any argument that there was an hypothesis consistent with the appellant’s innocence and unanimously dismissed the appellant’s appeal against conviction’.

Guilt beyond reasonable doubt?

HCA 28 – para 36 ‘On Dr Henry’s evidence, including that extracted above, the prosecution’s main contention, that the appellant’s DNA in Sample 3B derived from the appellant’s blood, was not made out beyond reasonable doubt. Secondly, Dr Henry’s evidence was not that secondary transfer of DNA was “rare”; rather, she said that a primary transfer is a much more likely source of contact or trace DNA than a secondary transfer, but that nevertheless a secondary transfer of contact or trace DNA is possible. There was no conflict in the evidence that there were at least two distinct occasions, described above, on which a secondary transfer of the appellant’s DNA to the didgeridoo may have occurred. Thirdly, the recovery of the appellant’s DNA from the didgeridoo did not raise any inference about the time when or circumstances in which the DNA was deposited there. For those reasons, it could not be accepted that the evidence relied on by the prosecution was sufficient to establish beyond reasonable doubt that the appellant was present at, and participated in, the attack. The jury, acting reasonably, should have entertained a reasonable doubt as to the appellant’s guilt. Alternative hypotheses consistent with the appellant’s innocence, in particular the hypothesis that Sumner transferred the appellant’s DNA to the didgeridoo on Sumner’s first visit to the house on the day in question, were not unreasonable and the prosecution had not successfully excluded them. As the evidence was not capable of supporting the appellant’s conviction for either offence, no question of an order for a new trial arose’.

This matter at first instance, clearly turned on the DNA evidence, which can be broadly simplified [for these purposes] to the blood like stains and the DNA transfer evidence. The expert accepted that the stains may not be blood, and that the defendants DNA could have been transferred into the scene by Mr Sumner. Whilst accepting these crucial findings, the expert also evidenced verbal probabilities which pointed significantly away from these findings.

The High Court correctly questioned the evidence and quashed the conviction, though it stopped short of identifying the underlying scientific assumptions, weightings and probabilities presented in this matter.  It is those unchallenged opinions as to probability, that were seemingly presented in the absence of supporting data, which may very well have contributed to the jury’s perception of the DNA evidence, when finding guilt.

Assigning DNA expert verbal probabilities in court

It is widely accepted within the forensic community, that expert opinion as to probabilities in evidence shall not be speculative and shall only be based on an auditable body of knowledge. The use of a verbal qualifier is not precluded, however, a verbal qualifier cannot be used in isolation of a numerical qualifier. A numeric likelihood ratio (numerical qualifier) must be evidenced when using verbal qualifiers.

The International Society of Forensic Genetics (ISFG) [4] states;

“The verbal scale is optional but cannot be used by itself. If it is used, then the numeric equivalents must also be available/provided. In practise, one would provide first one’s likelihood ratio, then the verbal equivalent is applied afterwards”.

The European Network of Forensic Science Institutes (ENFSI) Guideline [5] states;

“These probability assignments shall still be expressed by a number between 0 and 1 rather than by an undefined qualifier (such as frequent, rare, etc.). Such personal probability assignment is not arbitrary or speculative, but should be based on a body of knowledge that should be available for auditing and disclosure.” 

In a paper titled Dealing with DNA evidence in the courtroom, published in the Wrongful Conviction Law Review in 2020 [6], Weathered et al formed the following opinion in relation to the Fitzgerald matter:

“While the authors agree with the High Court’s decision, this case nevertheless highlights a question for criminal justice systems more broadly as to whether DNA transfer evidence is properly understood and evaluated, whether there is an appreciation of the limitations and potential error involved in this kind of evidence, and whether there is an awareness of the underlying assumptions used by scientists to rank the DNA transfer scenarios”.

How Fitzgerald can repeat itself in 2024

The question remains open, as to whether we have substantially learned the lessons of Fitzgerald.

When reviewing modern era DNA wrongful convictions, the significant commonality is a failure to tender DNA expert witness testimony in defence.

In Australia, a study of 55 trials found that the defence retained an expert in only about a third of those trials and in the majority of cases looked at, ‘the prosecution called a few experts and the defence called none’. [7]

Our adversarial justice system is predicated on prosecution and defence conducting a thorough interrogation of the evidence, in a concerted effort to determine its relative strength and weakness, as it relates to their respective hypothesis.

Most lawyers confronted with incriminating DNA evidence encourage their clients to plead guilty and few challenge the evidence or go beyond the low hanging fruit. [8]

The relevant 2014 scientific theory considered in Fitzgerald, is substantially unchanged in 2024. Should the given set of scientific evidence repeat itself today, and that evidence not be challenged by expert testimony, it is my experience that a guilty verdict remains a very real possibility.

The legal community has taken to understanding DNA evidence with great vigour and it would be reasonable to say that DNA evidence is understood by the legal community to a greater extent and more deeply, that it does understand any other forensic science. In the Fitzgerald matter, it seems on the face of it that the lawyers and judiciary had a good understanding of the science from a broad-brush perspective, they did not however appear to have a scientifically robust comprehension of all facets.

Various influential participants within science and law advocate for a greater knowledge of DNA within the legal profession. My perspective is that great caution should be taken with such an approach, should such an approach lead to an expectation.

An approach that levels responsibility on lawyers and judges to thoroughly comprehend and dissect the intricacies of scientific evidence, places an unrealistic expectation on the judicial process and does little to avoid the risk of Fitzgerald occurring again.

References

[1] Fitzgerald v The Queen ]2014] HCA 28 (13 August 2014)

[2] Lang v The Queen [2023] HCA 29 (11 October 2023)

[3] Makita (Australia) Pty Ltd v Sprowles

[4]  Gill, P., et al., DNA commission of the International society for forensic genetics: Assessing the value of forensic biological evidence – Guidelines highlighting the importance of propositions. Part II: Evaluation of biological traces considering activity level propositions. Forensic Sci Int Genet, 2020. 44: p. 102186.

[5] Institutes, E.N.o.F.S., ENSFI Guideline for Evaluative Reporting in Forensic Science. 2015. v3.

[6] Dealing with DNA evidence in the courtroom, published in the Wrongful Conviction Law Review in 2020

[7] Freckleton et al

[8] Gary Edmond, “The building blocks of forensic science and law”