R v GK - [2001] NSWCCA 413

No judgment structure available for this case.

Reported Decision:
125 A Crim R 315

New South Wales

Court of Criminal Appeal

CITATION: REGINA v GK [2001] NSWCCA 413

FILE NUMBER(S): CCA 60738/00

HEARING DATE(S): 1 May 2001

JUDGMENT DATE:
16 October 2001

PARTIES :

REGINA v GK

JUDGMENT OF: Mason P at 1; Sully J at 62; Dowd J at 102

LOWER COURT JURISDICTION: District Court

LOWER COURT FILE NUMBER(S) : 99/21/3063

LOWER COURT JUDICIAL
OFFICER : Moore DCJ

COUNSEL : Crown: R D Ellis
Respondent: P Byrne SC/M A Marty

SOLICITORS: Crown: S E O'Connor
Respondent: Greg Walsh & Co

CATCHWORDS: Evidence - whether judge at subsequent trial required to follow ruling of prior judge on admissibility of evidence - s137 Evidence Act 1995 - whether trial Judge should have allowed numerical probability evidence derived from DNA testing to go to jury - paternity index - relative chance of paternity statistics - Bayes' Theorem - whether probative value outweighed by risk of unfair prejudice - "prosecutor's fallacy". (D)

CASES CITED:
Annot 84 ALR 4th 313
Arnotts v Trade Practices Commission (1990) 24 FCR 313
Burger King Corporation v Hungry Jack's Pty Ltd [2001] NSWCA 187
Chamberlain v The Queen (No 2) (1984) 153 CLR 521
Doheny and Adams [1997] 1 Cr App R 369
Duke (1979) 22 SASR 46; 1 A Crim R 39
Gibson v R [2001] TASSC 59
Hassett [1999] EWCA Crim 1481
HG v The Queen (1919) 197 CLR 414
Humphrey (1999) 103 A Crim R 434
Latcha (1998) 104 A Crim R 390
Makita (Australia) Pty Ltd v Sprowles [2001] NSWCA 305
Milat (1996) 87 A Crim R 446
Mitchell (1997) 98 A Crim R 32
Ordukaya v Hicks [2000] NSWCA 180
Pantoja (1996) 88 A Crim R 554
Papakosmas v The Queen (1999) 196 CLR 297
People v Leonard (1997, 569 NW 2d 663, appeal denied 570 NW 2d 659)
Perry v The Queen (1982) 150 CLR 580
R v Denis Adams (No 2) [1998] 1 Cr App R 377
R v BD (1997) 94 A Crim R 131
R v Edwards (1997) 94 A Crim R 204
R v Karger [2001] SASC 64
R v Gallagher [2001] NSWSC 462
R v Jarrett (1994) 62 SASR 443
R v Kami (District Court of New South Wales 14 May 2001)
R v Noll [1999] VSCA 164
Reg. v Prasad (1979) 23 SASR 161
Rogers v The Queen (1994) 181 CLR 251
State v Freeman (1997, 571 NW 2d 276)
State Government Insurance Commission v Laube (1984) 37 SASR 31
State of Nebraska v Champ (20 March 2001, No A-00-617)
State v Carter 524 NW 2d 763
Steffen v Ruban [1966] 2 NSWR 622
Toki (2000) 116 A Crim R 536
United States v Davis (1994, 40 F 3d 1069, cert den (US) 131 L Ed 2d 239)

DECISION: Question 1. Where a trial Judge makes a discretionary ruling on the admissibility of certain evidence is a trial Judge at a subsequent trial following a failure by the first jury to agree on its verdict bound to follow that ruling with respect to the admissibility of the same evidence?; Answer: No.; Question 2. Was his Honour Judge Moore in error in refusing to admit evidence of the probability, in numerical terms derived from DNA testing, that …..(GK)…… was the father of the complainant's child, on the basis that there was a real risk of unfair prejudice to the accused?; Answer: Yes as to Paternity Index Statistics; No as to Relative Chance of Paternity Statistics.

IN THE COURT OF
CRIMINAL APPEAL

CCA 60738/00

MASON P

SULLY J

DOWD J

Tuesday 16 October 2001

REGINA v GK

The New South Wales Director of Public Prosecutions submitted two questions of law to the Court of Criminal Appeal, under s.5A(2) of the Criminal Appeal Act 1912 (NSW) .

The questions arose out of the trial of GK, on charges of sexual assault involving GK’s step-daughter, the complainant. At trial in September 1999 the Crown sought to prove that GK was the father of the complainant’s baby by tendering evidence of certain DNA testing. Objection was taken to this evidence under s137 of the Evidence Act 1995 (NSW). Following a voir dire, Ford DCJ limited admissibility to evidence that the testing did not exclude the possibility of paternity. He refused to allow evidence of likelihood or the percentage of probability of paternity.

GK was re-presented for trial in February 2000 before Moore DCJ and a jury. The Crown sought to lead evidence of further DNA testing which had been carried out since the first trial. Moore DCJ conducted a voir dire in which experts called by the Crown gave evidence about the interpretation of the DNA testing. Moore DCJ held that legal principles required him “not to disturb the exercise of the discretion from that which was exercised by his Honour Judge Ford”. He ruled that “there should not be arithmetical figures put before the jury”. This second trial aborted and a third was conducted on the basis of the rulings in the second. The jury finally returned a verdict of not guilty upon all eight counts in the indictment.

The questions the Director submitted to the Court were:

1. Where a trial Judge makes a discretionary ruling on the admissibility of certain evidence is a trial Judge at a subsequent trial following a failure by the first jury to agree on its verdict bound to follow that ruling with respect to the admissibility of the same evidence?

2. Was his Honour Judge Moore in error in refusing to admit evidence of the probability, in numerical terms derived from DNA testing, that … (GK) … was the father of the complainant’s child, on the basis that here was a real risk of unfair prejudice to the accused?

Held, by Mason P, Sully and Dowd JJ:

Question 1

(Per Sully J, Mason P and Dowd JJ concurring)

1. The first question is answered No.
2. A Judge who is asked to exclude evidence under s137 of the Evidence Act is not required to exercise any discretion such as is required, for example, under s135. The Judge is required to make a connected series of findings of law and of fact upon which s137 will operate without any further discretionary input of the Judge.
3. A particular ruling that some piece of evidence either is, or is not, required by the operation of s137 to be excluded can be re-visited by the trial Judge at any time until the Crown and the accused have finally closed their cases. The evidentiary ruling is then final for as long as the verdict remains on foot, unless the ruling is shown to have been tainted by fraud, or if fresh evidence, the acceptance of which will change the findings fundamental to the earlier ruling, is shown to exist.
4. Should the verdict be set aside on appeal, the Judge presiding at the re-trial will not be bound to accept the earlier ruling. This also follows in a case where the jury at the earlier trial could not reach a verdict.

Rogers v The Queen (1994) 181 CLR 251; R v Edwards (1997) 94 A Crim R 204 (applied).

Question 2

(Per Mason P, Dowd J concurring and Sully J)

unfair

prejudice”

“

R v BD

Papakosmos v The Queen

Ordukaya v Hicks

Toki

R v Karger; R v Kami

Mitchell

Gibson v R

Duke

Pantoja

5. Discussion of Bayes’ Theorem. ( Doheny v Adams [1997] 1 Cr App R (cited)). It is inappropriate for a jury to be invited to determine guilt by the application of mathematical formulae suggesting how to aggregate the impact of different items of evidence.
6. Discussion of directions to jury. R v Lissof [1999] NSWCCA 364.
7. Discussion of “The Prosecutor’s Fallacy”. Latcha (1998) 104 A Crim R 390; Doheny and Adams ; R vJarrett (1994) 62 SASR 443 (discussed). Milat (1996) 87 A Crim R 446 (cited).

ORDERS:

Where a trial Judge makes a discretionary ruling on the admissibility of certain evidence is a trial Judge at a subsequent trial following a failure by the first jury to agree on its verdict bound to follow that ruling with respect to the admissibility of the same evidence?

Was his Honour Judge Moore in error in refusing to admit evidence of the probability, in numerical terms derived from DNA testing, that …..(GK)…… was the father of the complainant’s child, on the basis that there was a real risk of unfair prejudice to the accused?

*************

CCA 60738/00

MASON P

SULLY J

DOWD J

Tuesday 16 October 2001

REGINA v GK

JUDGMENT

I have had the benefit of reading the judgment of Sully J.

2 The first question submitted for this Court's determination is:

1. Where a trial Judge makes a discretionary ruling on the admissibility of certain evidence is a trial Judge at a subsequent trial following a failure by the first jury to agree on its verdict bound to follow that ruling with respect to the admissibility of the same evidence?

3 This question is too broadly stated to be very useful. And, for the reasons given by Sully J, it is misleading in inferring that a decision to reject evidence pursuant to s137 of the Evidence Act 1995 is a "discretionary ruling".

4 Furthermore, I understand the parties to accept that a jury's failure to agree upon a verdict at an earlier trial precludes the application of the principles in Rogers v The Queen (1994) 181 CLR 251 to an evidentiary ruling in the earlier trial. It is the rendering of a verdict that gives relevant finality to the evidentiary rulings upon which it was based, so long as the verdict itself stands (Rogers at 279-80, R v Edwards (1997) 94 A Crim R 204).

5 Since the ruling of Ford DCJ concerned evidence which was tendered in relation to counts upon which the jury ultimately failed to render a verdict, it was wrong for Moore DCJ to have approached the ruling in the earlier trial as if it had any preclusive effect. Judge Moore spoke in terms of being limited by "the same principle applied by the Court of Appeal in determining whether a Judge has exercised a discretion fairly". The respondent contends that the remarks just quoted do not fairly represent his approach to the evidentiary task before him. In the upshot, it is unnecessary to consider the matter further in the disposition of this appeal, which is limited to issues of general principle.

6 I agree with what Sully J has written in relation to the general issues arising under the first question; and with his proposed answer "No".

7 The second question submitted for the Court's decision is:

2. Was his Honour Judge Moore in error in refusing to admit evidence of the probability, in numerical terms derived from DNA testing, that …..(GK)…… was the father of the complainant’s child, on the basis that there was a real risk of unfair prejudice to the accused?

8 The Crown was seeking to prove that the respondent GK had had sexual intercourse with his step-daughter, the complainant. She had had a child (C) and there had been DNA paternity testing based on samples taken from GK and C.

9 The matter in issue is the admissibility of statistical evidence as to the likelihood of paternity. Sully J sets out the facts. There was no challenge to the relevance of the evidence. Indeed, its probative weight is the reason why it is said that evidence of this nature should be kept from the jury.

10 Moore DCJ held that it was open to the Crown to lead evidence that the DNA testing showed that the accused could be the father. But he ruled that “there should not be the arithmetical figures put before the jury”. In doing so, his Honour effectively adopted the similar ruling given by Ford DCJ in an earlier trial of the respondent. Judge Ford had said:

I think the evidence should be limited so that there is merely an expression of opinion as to the scientific view; that the testing does not exclude the possibility of paternity. So the evidence of likelihood and certainly the evidence as to percentage should be excluded….. And I say that because I think there is a very considerable risk that the jury notwithstanding any blandishments on my part may take the practical position of a punter and say this is not just a mere certainty but an absolute certainty.

11 The figures were provided by two scientists called by the Crown whose expertise was not in issue. Each witness said that the DNA testing showed more than that GK could be the father of C. They explained the processes and statistical assumptions lying behind the figures derived as to the statistical probability that GK was C’s father. Parts of their evidence were challenged in cross-examination, but the exclusion of the figures was not based upon rejection of the reliability of the scientific evidence. Rather, it was based on s137 of the Evidence Act which provides:

137. In a criminal proceeding, the court must refuse to admit evidence adduced by the prosecutor if its probative value is outweighed by the danger of unfair prejudice to the defendant.

12 Mr Goetz had said that the statistical analysis of the results using 10 different markers could be expressed as follows:

Paternity Index: 220,000:1

13 Dr Gunn’s statistical representation of the results using 12 different markers were:

Paternity Index: 147,005:1

14 Each expert explained the concepts of paternity index and relative chance of paternity.

15 Mr Goetz said that a paternity index is:

… the odds in favour of paternity. Verbally it would be given as it is 220,000 [times] more likely that [GK] is the biological father of [C] than anybody else taken at random in the population.

16 He explained the relative chance of paternity as:

… a value which is really related to the paternity index. It’s a re-calculation of the paternity index. However, I’d prefer to stay with the paternity index. I think it’s easier to understand.

17 In cross-examination he gave the following additional evidence (Tr pp16-17).

Q. And it’s a reversal from an exclusionary position to an inclusionary one isn’t it?

A. No, they’re both inclusionary positions. One’s saying that the probability of paternity is an odds, and the other one is giving a percentage. Now the percentage is more complicated to explain and therefore that’s why I’m staying with the odds. I think the odds most people are familiar with.

Q. So you agree that the percentage as calculated from the odds is misleading in that sense?

A. No I don’t think it’s misleading, the problem is it was easy when you had a 99 per cent probability paternity. That was 100 to 1. As DNA testing has increased the nines have increased and therefore it becomes more complicated to explain what this 99 with all these nines after it mean. Whereas a number like 200,000 or 50,000 or 500,000,000 are quite easy to explain. People can understand that.

Q. But the problem with a percentage is this, is it not, that DNA testing can never prove that someone is the father of someone else, can it?

A. I absolutely agree with that, we can never give 100 per cent there.

Q. All it can do is exclude someone from being the father of someone else, can’t it?

A. No I don’t agree with that. Obviously it can exclude someone, but if it can’t exclude someone then really everybody needs to know how important is that evidence. If one uses only – if I use only one DNA test here, say the first one, and I got an odds of 5 to 1 and I wanted to go to Court and say well, you know, I’ve got great results here, 5 to 1, I can’t exclude him, but really the 5 is fairly inadequate evidence because it’s saying that he’s five times more likely to be the father and therefore there’s heaps of people in the population who could also be the father. But if I multiply my numbers together then I’m also increasing the probability that someone else in the population cannot be the father. And that’s also important to be aware of.

Q. So you would say in this case, wouldn’t you, that the chances of finding someone in the general population at random with the same DNA profile as [GK] would be 140,000 to 1, true?

A. No, I’d say he’s 140,000 more likely to be the father than someone else taken at random in the population.

Q. But is my proposition incorrect, it’s not is it?

A. I’m not really sure. I get very confused with the rewordings that lawyers make of it and I try to stay strictly on the way that I explain it because I know mine’s correct. Statisticians get very angry when it’s worded the wrong way and sometimes I cannot work out the right way from the wrong way. And actually a lot of statisticians can’t either. Whereas I believe my way of saying it is the correct way of saying it. It’s 140,000 times more likely that he is the father of the child than anybody else taken at random in the population.

Q. So you disagree that that is – well you say that is not the same as saying that the chances of finding someone in the general population with his DNA profile is 140,000 to 1?

A. I’m not saying that it’s not the same, I’m saying that I prefer my wording to the way you’ve worded it.

18 Dr Gunn explained paternity index and relative chance of paternity in the following terms (Tr pp22-3, 25):

Q. Just for the case of completeness could you explain what is meant by paternity index?

A. Yes, the paternity index is a way of estimating the strength of the evidence from any particular genetic locus examined. For example on page 2A the first locus looked at, CSF1P0, we can tell that the child must have inherited the gene designated number 10 from its biological father. There are two explanations for the result, either [GK] really is the father of the child or just by coincidence he also has the 10 characteristic. The paternity index is a way of weighting those two possibilities. In that particular example, it’s about 1.99 times more likely that he would – that he is the biological father than that he just has that characteristic by coincidence. The same logic is applied to all of those 12 tests and then the final figure, the paternity index, is the combination of those 12 ---

Q. Multiplied ---

A. ---multiplied together, yes.

Q. That is known as the product rule?

A. Yes.

Q. The paternity index that you came to when you did your testing in your report on September 11 1998 was what?

A. The paternity index was 147,005 to 1.

Q. And the relative chance of paternity?

A. Yes, the relative chance of paternity, which is really expressing that index as a percentage, was 99.9993 per cent.

Q. In your experience are they high results?

A. They are high, they’re not unusually high for DNA testing but they are high results.

…

Q. What’s the correct way of wording the paternity index, is it the chance that a person selected from the community at random could be the father is 1 in 534 odd million?

A. Not really, it’s a matter of semantics to some extent but probably the best way of putting it is that for [the complainant] to produce a child with this genetic pattern, it is about 500 million times more likely that she would do that with [GK] as the father than she would with another random person that was the father.

Q. And how was the relative chance of paternity, what’s the best way to describe that?

A. That’s really just the same number but expressed as a percentage rather than as a ratio of odds.

19 The admissibility of evidence based on DNA matching is not in dispute in this appeal. That scientific issue (based in part upon statistical analysis) has recently been considered at length in R v Karger [2001] SASC 64 (Mullighan J) and R v Gallagher [2001] NSWSC 462 (Barr J). See also Milat (1996) 87 A Crim R 446, Pantoja (1996) 88 A Crim R 554, R v Noll [1999] VSCA 164. We are not concerned with the debate about racial sub-groups and DNA, or the possibility that a close relative of the defendant committed the crime. The rejection of the evidence in question was not based on questioning the accuracy of DNA statistical analysis or its capacity to point towards guilt.

20 Nor was the evidence of the Crown experts rejected on the basis of lack of relevant expertise or failure to state the detailed grounds and assumptions upon which conclusions as to statistical probabilities were based (cf Makita (Australia) Pty Ltd v Sprowles [2001] NSWCA 305). The ruling that excluded such evidence did not turn upon s79 of the Evidence Act or the principles discussed in the cases cited at par 30 below.

21 Nor does this appeal involve an attempt to use Bayes’ Theorem as a method for the jury to piece together the impact of discrete items of evidence tendered as proof of guilt. That Theorem offers a numerical probability weighting to other pieces of evidence that bear on the likelihood of an event happening. The Theorem shows the effect of a new item of evidence on a previously established probability (see Aitken & Storey, the Use of Statistics in Forensic Science, 1991 at p119ff and McCormick on Evidence 4th ed §211 for discussions of the Bayesian method). The Theorem underpins the statistics professed by the experts based upon what was described as the product rule. But that is something quite different to an invitation to the jury to follow suit in their analysis of the totality of evidence.

22 In Doheny and Adams [1997] 1 Cr App R 369 at 375 the English Court of Appeal strongly endorsed the comment in Adams [1996] 2 Cr App R 467 at 482 that:

To introduce Bayes Theorem, or any similar method, into a criminal trial plunges the jury into inappropriate and unnecessary realms of theory, and complexity deflecting them from their proper task.

R v Denis Adams (No 2)

Karger

23 This appeal involves the admissibility of statistical information interpreting the outcome of DNA testing. I am not suggesting that the defence was accepting everything that the experts were saying – quite the contrary. But the question at issue under the s137 ruling was whether this evidence should be withheld from the jury because it had probative value that was outweighed by the danger of unfair prejudice to the defendant.

24 The presumption of innocence can only be displaced if the jury are persuaded of guilt beyond a reasonable doubt. It is their task alone.

25 Statistics is a branch of science. In a criminal trial conflicts of evidence, even scientific and statistical evidence, are to be resolved by the jury as the constitutional judge of fact (Chamberlain v The Queen(No 2) (1984) 153 CLR 521 at 558, 598, R v Jarrett (1994) 62 SASR 443).

26 The process of assessing the weight of different items of evidence and reasoning to a conclusion on the civil or criminal standard cannot be reduced to mathematical formulae. In an article on “Probability and Proof in Legal Fact Reasoning” (1995) 69 ALJ 731 at p736, the Hon Mr Justice D H Hodgson said that “decision-making generally involves a global assessment of a whole complex array of matters which cannot be given individual numerical expression”. He warned that concentration on mathematical probabilities can prejudice the common sense process which depends upon experience of the world and belief as to how people generally behave (see also State Government Insurance Commission v Laube (1984) 37 SASR 31 at 32-3, Mitchell (1997) 98 A Crim R 32 at 37-8, Burger King Corporation v Hungry Jack’s Pty Ltd [2001] NSWCA 187 at [591]).

27 It is therefore inappropriate to determine guilt by the application of mathematical formulae suggesting how to aggregate the impact of different items of evidence. That is why Bayes Theorem has been rejected in this area. But it does not follow that the mathematics of probability is to be kept out of the courtroom. In the article referred to, Mr Justice Hodgson suggests various roles for statistical evidence as items of individual proof.

28 There are, however, particular dangers, to those who are uneasy with mathematics and untrained in statistics. In Perry v The Queen (1982) 150 CLR 580 at 594 Murphy J said:

It is very easy to assume that in common experience a person is hardly ever associated with poisonings of four close relatives, and that if such an association occurs it is so remarkable that it is unlikely to be innocent. Common assumptions about improbability of sequences are often wrong. A suggested sequence, series or pattern of events is often incorrectly regarded as so extremely improbable as to be incredible. However highly improbable, as well as merely improbable, sequences and combinations are constantly occurring. In random tossing the occurrence of a run of ten consecutive heads or tails is generally regarded as highly improbable. But this will occur on the average once in every 512 tosses, and the lesser sequences more frequently (2 runs of 9; 4 runs of 8; 8 runs of 7). If one randomly tosses a coin 257 times, more likely than not there will be a sequence of ten heads or tails. Although it is extremely improbable that any particular ticket will win a large lottery, it is certain that one will.

(A wiser mind than mine has suggested that the mathematics are not quite accurate, but this does not affect the point Murphy J was making.)

29 The court has a legitimate concern that evidence is capable of being understood by a jury of ordinary citizens. There will be “unusual cases in which the judge has reason to fear that the jury will be overawed by the scientific garb in which the evidence is presented and will attach greater weight to it than it is capable of bearing” (Duke (1979) 22 SASR 46 at 48, 1 A Crim R 39 at 41 per King CJ. See also Pantoja (1996) 88 A Crim R 554 at 561-2).

30 Section 137 requires the exclusion in criminal proceedings of evidence adduced by the prosecutor if its probative value is outweighed by the danger of unfair prejudice to the defendant. The key term is “unfair prejudice” in the sense of evidence creating “a real risk that the evidence will be misused by the jury in some unfair way” (R v BD (1997) 94 A Crim R 131 at 139 per Hunt CJ at CL. See also Papakosmas v The Queen (1999) 196 CLR 297 at 325-6, Ordukaya v Hicks [2000] NSWCA 180, R v Lisoff [1999] NSWCCA 364 at [52], Toki (2000) 116 A Crim R 536 at 548). Merely because evidence points overwhelmingly to guilt does not make it unfair to adduce it. And even if evidence carries a prejudicial overlay its genuine probative value must be put in the scales.

31 The judge presiding over a criminal trial may therefore have to ensure that careful directions and warnings are given to ensure that the jury understands its role and understands exactly what the scientific evidence does and does not tend to prove. This judicial function is the backdrop to any consideration about exclusion of evidence pursuant to s137. I respectfully endorse the following propositions stated by this Court (Spigelman CJ, Newman J, Sully J) in Lisoff at [49]:

49. … [It] is, in our opinion, necessary to be clear about certain fundamental propositions which we would express as follows:

1. The status in our system of criminal justice of a jury at trial is of absolutely fundamental constitutional legitimacy and importance. The empanelling of a lay jury, chosen at random from the general body of citizens, to be the sole tribunal of fact is not some irksome survival from a feudal past, whether real or imagined. The contribution of lay juries to our system of criminal justice is the lynch-pin of that system.

The importance of the jury in our criminal justice system is such as to justify attributing to the jury a constitutional significance even where there is no express constitutional protection such as that provided by s.80 of the Commonwealth Constitution. Statutes will not be interpreted ,therefore, as impinging on the right to trial by jury unless there is clear and unambiguous language to that effect.

2. It would be to close one's eyes to what is going on in contemporary society not to recognise that there is a body of articulate opinion which holds that a lay jury drawn at random in accordance with current principle and practice is, more or less as of course, unable to be entrusted safely with the decision of questions of fact which are said to be complex, or of a highly technical nature. There is, more often than not, more than just a touch of elitism and of intellectual condescension in the point of view.

But the real flaw in the point of view is that it fails wholly to take account of the everyday practical experience of the courts in their dealings with juries empanelled in criminal trials.

3. That experience would, in our own observation and understanding of these matters, have to acknowledge, and to make allowance for, the case of the jury that fails, as a collegiate body, to do its sworn public duty.

The same would have to be said about individual jurors in particular cases. But it seems to us that the fair position is that such departures from proper jury standards are very much the exception rather than the rule. It is, in our opinion, demonstrably true as a general proposition that the average jury, if properly assisted and directed, will do diligently and conscientiously what the law asks of it.

4. That any jury in any criminal trial requires proper direction as to the relevant law, and proper practical assistance otherwise, entails a significant burden upon all the professionals who are engaged in the conduct of the particular trial. The brunt of that responsibility will be borne by the presiding judge whose duty it is to see that the jury receives proper direction and assistance, and receives it with a proper patience and courtesy. There is a different, but no less compelling, professional duty resting upon those who prosecute and defend in the particular case.

5. It is one thing to say that, in such a case as is exemplified by the present particular case, it will be, obviously, difficult to put into simple lay language the concepts which the jury must have firmly in its grasp; and to assist the jury with a similar clarity and simplicity to apply those concepts to the evidence adduced in the trial, both by the prosecution and by the defence. It is, however, an entirely different thing to take it as, more or less, self-evident that the jury, even if given that assistance, will be either unwilling or unable, or both, to carry out in a proper way the jury's critical fact-finding function.

32 What then is said to be the unfairly prejudicial nature of the statistical evidence excluded in the present case? The ruling of Ford DCJ (effectively adopted by Moore DCJ) states a fear that the jury may “take the practical position of a punter and say this is not just a mere certainty but an absolute certainty”, notwithstanding proper judicial directions. I will describe this as a “broad brush” concern about DNA statistics. In doing so, I acknowledge that this was an extempore ruling given in the course of a trial. Yet my wider reading shows a recurring theme of concern based upon the very strength of DNA evidence.

33 There is, however, a narrower basis for concern. It lies in the fear that the jury may not understand the non-inclusionary nature of the statistical evidence. Using Dr Gunn’s paternity index figure, the fear is that the jury would elide two different propositions:

A. The probability or chance of C’s father being a person selected at random rather than being GK is 147,005:1 against.

34 The slide from Proposition A to Proposition B is an example of what is known as “the prosecutor’s fallacy”. This is a phenomenon discussed in the literature and case law surrounding DNA profiling, but not confined to the particular situation involved in the present case.

35 It is vital to separate the wheat from the chaff in addressing the issues that arise in relation to properly established statistical data relevant to DNA matching.

36 If ten unconnected eye witnesses identify X as the person whom they saw stab a victim, and if X were immediately apprehended by them thereby removing any identification issue, the evidence of guilt would amount to virtual certainty. Some of the witnesses might well give evidence expressing themselves as "100 percent certain" of what they saw. Yet no one would dream of seeking to have this evidence excluded pursuant to s137, for the simple reason that no unfair prejudice flows from the testimony.

37 It is not the judicial function to give the accused a fighting chance of gaining an acquittal, as if the trial were a horse race and the judge were a handicapper deciding how much weight to place in the Crown's saddlebags. The admissibility of evidence is not in an inverse ratio to its probative effect.

38 Experience teaches that witnesses can be "100 percent certain", yet wrong. And, so long as juries determine issues of guilt, jurors will be entitled to reject the confident testimony of lay and scientific witnesses, especially if it does not fit with other evidence that they do accept.

39 Accordingly, if relevant DNA statistical evidence is tendered through a witness of due expertise then its probative weight cannot itself be a ground for withholding it from the jury. Indeed its very significant probative weight is a factor in favour of admission notwithstanding the capacity of extremely high odds to carry a prejudicial overlay.

40 In New South Wales opinion evidence is not inadmissible only because it is about a fact in issue or an ultimate issue (Evidence Act, s80(a)). However, judges should exercise particular scrutiny when experts move close to the ultimate issue, lest they arrogate expertise outside their field or express views unsupported by disclosed and contestable assumptions (see Steffen v Ruban [1966] 2 NSWR 622 at 626, Arnotts v Trade Practices Commission (1990) 24 FCR 313 at 350-1, HG v The Queen (1919) 197 CLR 414 at 427-8, Makita).

41 As I shall explain, Doheny v Adams shows that it is easy for a DNA expert to be led unwittingly by prosecuting counsel into these murky waters. Avoidance of the prosecutor’s fallacy (discussed below) is a principal antidote.

42 The respondent contends for stronger medicine, namely rejection of statistical information as to the probabilistic strength of a DNA match. In my view, that is going too far. It is contrary to the propositions about complex scientific evidence in criminal trials that I have endeavoured to summarise above. The total exclusion of “arithmetical figures” skews the experts’ evidence without contributing to the fairness of the trial. The prosecution case might be prejudiced: but no contribution would be made to the avoidance of unfair prejudice to the defence case.

43 The admissibility of a likelihood ratio derived from DNA testing is supported by Karger (at [663]) and the ruling given by Judge Shadbolt in R v Kami (District Court of New South Wales 14 May 2001). (In Kami the evidence was admitted, yet the accused were acquitted.) See also Mitchell (1997) 98 A Crim R 32 at 44, where Higgins J appears to endorse admission of such evidence subject to the jury being given a warning as to the use they should make of it.

44 In Gibson v R [2001] TASSC 59, the Tasmanian Court of Criminal Appeal recently considered the admissibility of DNA profiling in criminal proceedings for rape in which the identity of the assailant was the sole issue. DNA profiles were taken of sperm taken from the victim and blood taken from the appellant. At issue was the admissibility of scientific evidence to the effect that a comparison of the profiles showed that each was consistent with the other and that “the chance of a second person unrelated to [the appellant] having the same DNA profile is less than one in a hundred million”. The Court (Underwood, Slicer and Evans JJ) held that the statistical evidence was properly admitted.

45 American case law has wrestled with the issue of the prejudicial impact upon criminal juries of statistical calculations associated with DNA testing (see Annot 84 ALR 4th 313. For a window into the vast American literature and case law, see McCormick on Evidence §§205B, 209). The trend of recent decisions indicates a fairly clear move towards admissibility (ibid, Supplement; United States v Davis (1994, 40 F 3d 1069, cert den (US) 131 L Ed 2d 239), People v Leonard (1997, 569 NW 2d 663, appeal denied 570 NW 2d 659), State v Freeman (1997, 571 NW 2d 276). A recent review of the American case law concluded that:

It appears that the majority of other states’ courts share the view that evidence of a DNA match without accompanying statistical interpretation is meaningless and inadmissible.

People v Coy

46 Evidence is admitted on the basis that the jury will be properly instructed as to its use. It is wrong to exclude evidence merely because it was capable of being misunderstood or misused.

47 But there are real dangers in misunderstanding the statistics in this area (for some empirical evidence of this, see Thompson and Schumann, “Interpretation of Statistical Evidence in Criminal Trials: The Prosecutor’s Fallacy and the Defence Attorney’s Fallacy” (1986) 10 Law & Human Behaviour 167).

48 In Doheny and Adams Phillips LJ (as he then was) said this (at 372-3):

“The Prosecutor’s Fallacy”

It is easy, if one eschews rigorous analysis, to draw the following conclusion:

1. Only one person in a million will have a DNA profile which matches that of the crime stain.

2. The defendant has a DNA profile which matches the crime stain.

3. Ergo there is a million to one probability that the defendant left the crime stain and is guilty of the crime.

Such reasoning has been commended to juries in a number of cases by prosecuting counsel, by judges and sometimes by expert witnesses. It is fallacious and it has earned the title of “The Prosecutor’s Fallacy”. … The nature of that fallacy was elegantly exposed by Balding and Donnelly in “The Prosecutor’s Fallacy and DNA Evidence” [1994] Crim LR 711. It should not, however, be thought that we endorse the calculations on pp715 and 716 of that article.

Taking our example, the prosecutor’s fallacy can be simply demonstrated. If one person in a million has a DNA profile which matches that obtained from the crime stain, then the suspect will be 1 of perhaps 26 men in the United Kingdom who share that characteristic. If no fact is known about the Defendant, other than that he was in the United Kingdom at the time of the crime the DNA evidence tells us no more than that there is a statistical probability that he was the criminal of 1 in 26.

The significance of the DNA evidence will depend critically upon what else is known about the suspect. If he has a convincing alibi at the other end of England at the time of the crime, it will appear highly improbable that he can have been responsible for the crime, despite his matching DNA profile. If, however, he was near the scene of the crime when it was committed, or has been identified as a suspect because of other evidence which suggests that he may have been responsible for the crime, the DNA evidence becomes more significant. The possibility that two of the only 26 men in the United Kingdom with the matching DNA should have been in the vicinity of the crime will seem almost incredible and a comparatively slight nexus between the defendant and the crime, independent of the DNA, is likely to suffice to present an overall picture to the jury that satisfies them of the defendant’s guilt.

The reality is that, provided there is no reason to doubt either the matching data or the statistical conclusion based upon it, the random occurrence ratio reduced from the DNA evidence, when combined with sufficient additional evidence to give it significance, is highly probative. As the art of analysis progresses, it is likely to become more so, and the stage may be reached when a match will be so comprehensive that it will be possible to construct a DNA profile that is unique and which proves the guilt of the defendant without any other evidence. So far as we are aware that stage has not yet been reached.

49 In Latcha (1998) 104 A Crim R 390 the Court of Appeal of the Northern Territory held that duly proved and scientifically valid statistical evidence could be given about the “likelihood ratio” in a relevant population of a DNA match. (The Court was addressing a case involving a match between sperm taken from the panties of a sexual assault victim and the accused man’s blood.) However, the Court emphasised the need for care lest the jury confuse two questions:

50 See also Milat (1996) 87 A Crim R 446 at 451, Gibson v R [2001] TASSC 59 at [49].

51 As to the prosecutor’s fallacy, see also Redmayne, “Doubts and Burdens: DNA Evidence, Probability and the Courts” [1995] Crim LR 464 at pp474-6, Thompson and Schumann, op cit. (The latter article describes the Defence Attorney’s Fallacy as the suggestion that associative statistical evidence is irrelevant regardless of the rarity of the “matching” characteristics. What this reasoning fails to take into account is that the great majority of the pool of people with relevant matching are not suspects in the case against whom additional evidence is available linking them with the offence. On this, see also the passage from Doheny and Adams quoted above.)

52 I am not aware of any decision (apart from the trial rulings in the present case) where the risks inherent in this fallacious method of reasoning led to the complete rejection of (accurate and verified) statistical data of the “non-inclusionary” sort involved in the present case.

53 In Doheny and Adams, the English Court of Appeal considered statistical evidence based upon DNA testing to the effect that the chance of finding the profile in another unknown unrelated person was 1 in 40 million. The admissibility of the evidence was not in issue in that case, but nothing in the judgment suggests concern on that account. It was held that the verdict of the jury was unsafe because the forensic evidence was presented to the jury in a misleading and inaccurate manner, involving the Prosecutor’s Fallacy. An expert witness, Mr Davie concluded his evidence in chief as follows:

Q. What is the combination, taking all those into account?

A. Taking them all into account, I calculated the chance of finding all of those bands and the conventional blood groups to be about 1 in 40 million.

Q . The likelihood of it being anybody other than Alan Doheny?

A. Is about 1 in 40 million.

Q. You deal habitually with these things, the jury have to say, of course, on the evidence, whether they are satisfied beyond doubt that it is he. You have done the analysis, are you sure that it is he?

A. Yes.

54 Giving the judgment of the Court, Phillips LJ said of these three questions and answers (at 378):

The second question, in leading form, and the affirmative given to it constituted a classic example of the “Prosecutor’s Fallacy”. The third question was one for the jury, not for Mr Davie. Mr Davie gave an affirmative answer to it. It is not clear to what evidence, if any, other than the DNA evidence, he had regard when giving that answer. For the reasons that we gave in our introduction to this judgment, this series of questions and answers was inappropriate and potentially misleading. The questions should not have been asked of this witness. If the random occurrence ratio was, indeed, 1 in 40 million this nonetheless meant that there was a statistical possibility of several individuals in the United Kingdom having the same DNA profile as the assailant, of whom one was the appellant. It was for the jury to decide on all the evidence whether they were sure that it was the appellant who left the crime stain, or whether it might have been one of a handful of other persons who might exist in the United Kingdom sharing the same DNA profile.

55 The fact that experienced witnesses, prosecutors and judges have themselves committed variants of the prosecutor’s fallacy in dealing with DNA evidence (see Redmayne, op cit at p474 n68, Hassett [1999] EWCA Crim 1481) is reason for caution. Empirical research reinforces this (see Thompson and Schumann, op cit). Nevertheless, I cannot accept the correctness of Judge Moore’s ruling that no arithmetical figures should be placed before the jury. I would adopt the following remarks of Judge Sievers, speaking for the Superior Court of Nebraska in State of Nebraska v Champ (20 March 2001, No A-00-617):

… it is worth observing that DNA matches mean little without the statistical probability component, which relies on the Hardy-Weinberg equilibrium and product rule. … “Without the probability assessment, the jury does not know what to make of the fact that the patterns match: the jury does not know whether the patterns are as common as pictures with two eyes, or as unique as the Mona Lisa.” (

State v Carter

DNA science is accepted and admissible, there was no challenge to the methodology, and the evidence was that the DNA analysis was done in accordance with generally accepted scientific principles. Thus, while the evidence is obviously highly prejudicial to Champ, it is not unfairly so, and its probative value is great. There was no error in the use of the DNA evidence.

56 In Jarrett, Mullighan J declined to exclude expert evidence of DNA analyses and the statistical interpretation of those analyses. That was a stronger case than the present because the scientific experts were in conflict. His Honour cited well-known authorities about the jury’s role in resolving conflicts in the evidence. These included the following remarks of King CJ in Duke (1979) 22 SASR at 48, 1 A Crim R at 41 where he said:

There may be unusual cases in which the judge has reason to fear that the jury will be overawed by the scientific garb in which the evidence is presented and will attach greater weight to it than it is capable of bearing. It is to be remembered, however, that under our system, whatever criticisms of it there might be, the assessment of the weight to be attached to expert evidence, as to other evidence, is the function of the jury. That being the system, a trial judge must assume, in my view, that the jury is capable of understanding that it is not bound to accept the expert evidence, that it is capable of resolving conflicts of opinion amongst the expert witnesses, and that it will not be overawed by the scientific garb in which the evidence is presented to it.

57 Later in his judgment in Jarrett, Mullighan J said (at 455):

It is not immediately clear to me how admissible expert testimony which bears upon an important fact in issue may have a prejudicial effect on the minds of jury which far outweighs its probative value in the relevant sense. As King CJ observed in

Duke

(at 47-48):

The prejudice … must, of course, be a prejudice additional to or distinct from the detriment to the accused’s interests involved in the probative force of the evidence.

In order to be admissible, expert testimony must be relevant to a fact in issue and comply with well-known preconditions…. Once those preconditions are established, it is difficult to see how the evidence may have a prejudicial effect which far outweighs its probative value….

58 I agree.

59 It follows that the paternity index figures should not have been withheld from the jury pursuant to s137 of the Evidence Act. They should have gone to the jury accompanied by appropriate directions emphasising the need to avoid the prosecutor’s fallacy. This appeal is not the proper vehicle to formulate a model direction in that regard. I content myself with the suggestion that it would be desirable if, at the time the judge tells the jury that evidence of paternity has been expressed as a high or very high probability, the jury should be reminded then and there that the evaluation of that evidence is a matter for them in light of the totality of the expert and non-expert evidence.

60 However, I agree with Sully J that the exclusion of the relative chance of paternity percentage was appropriate. I agree with his Honour’s reasons and would add this consideration: Mr Goetz himself recognised that the relative chance of parentage percentage was “more complicated to explain”. I shall not endeavour to explain why, lest I reveal my own misunderstanding of relative chance of paternity expressed as a percentage, beyond observing that part of the difficulty would be removed if 99.9993% was transposed to a statement that there was a 0.0007% probability or chance of C’s father being anyone other than GK. Even such adjustment would leave me of the view that the evidence is unduly prejudicial in its impact.

61 The second question should therefore be answered, as proposed by Sully J: “Yes”, as to the Paternity Index statistics; “No”, as to the Relative Chance of Paternity statistics.

The New South Wales Director of Public Prosecutions has submitted for determination by this Court two stated questions of law. The right of the Director to do that derives from s.5A(2) of the Criminal Appeal Act 1912 NSW. It is there provided, relevantly:

“(2) (a) Where a person tried on indictment has been acquitted (whether in respect of the whole or part of the indictment) either before or after the commencement of the Criminal Appeal (Amendment) Act 1977 the Attorney-General or Director of Public Prosecutions may at any time after the conclusion of the trial submit for determination by the Court of Criminal Appeal any question of law arising at or in connection with the trial.

(b) The Attorney-General or Director of Public Prosecutions shall submit with the question to be determined a statement of the circumstances out of which the question arose and thereafter shall furnish such further statement as the Court of Criminal Appeal may require.

(c) The Court of Criminal Appeal shall hear and determine any question submitted to it under this subsection.

(d) The determination by the Court of Criminal Appeal of the question submitted shall not in any way affect or invalidate any verdict or decision given at the trial.

(e) Any person charged at the trial or affected by the decision shall be entitled to be heard before the Court of Criminal Appeal upon the determination of the question submitted, and if it appears that such person does not propose to be represented upon such determination, the Attorney-General or Director of Public Prosecutions shall instruct counsel to argue such question before the Court of Criminal Appeal on behalf of such person.

(f) The reasonable costs of legal representation of any person heard before the Court of Criminal Appeal as provided in this subsection shall be paid by the Crown.

(g) The hearing and determination of any question under this subsection shall be held in camera:

Provided that nothing in this paragraph shall preclude a barrister or solicitor from being present at the hearing and determination for the purpose of reporting the case for any lawful purpose of the Council of Law Reporting for New South Wales.

(h) No report of any submission made pursuant to paragraph (a) shall be published. No report of proceedings under this subsection shall be published which discloses the name or identity of the person charged at the trial or affected by the decision given at the trial. Any publication in contravention of the foregoing provision shall be punishable as contempt of the Supreme Court.”

63 It is necessary to recapitulate, before turning to the precise questions which have been submitted by the Director, the relevant background which is as follows.

64 In September 1999 G.K. was presented for trial before Ford DCJ and a jury in the Campbelltown District Court. He was so presented upon an indictment containing 14 counts. The complainant in all counts was G.K’s step-daughter. Some of the counts were counts of common assault; and the remainder of them were counts charging various offences of sexual impropriety. Some of the counts alleged sexual intercourse between G.K. and the complainant.

65 The upshot of that trial was that the jury found G.K. guilty of one charge of common assault; found him, by direction, not guilty of six other counts charged; and were unable to agree upon verdicts on the remaining seven counts in the indictment. By the time of this trial, the complainant had given birth to a baby boy, C. The Crown set out to prove, in aid of those charges involving an allegation of sexual intercourse between G.K. and the complainant, that G.K. was in fact the father of C. To that end the Crown tendered evidence of certain DNA testing. Objection was taken to the admission of that evidence. The transcript of the proceedings before Ford DCJ has not been included in the present appeal papers; but the materials that have been included in the present appeal papers suggest that Ford DCJ dealt with the objection upon the basis that the objection depended upon s 137 of the Evidence Act 1995 (NSW), [“the Evidence Act”]. It appears that Ford DCJ conducted a hearing on the voir dire in order to determine the admissibility of the challenged evidence. It appears, further, that Ford DCJ, at the conclusion of the submissions of counsel made in connection with the voir dire hearing, dealt briefly and ex tempore with the particular evidentiary issue. The relevant record discloses the following exchanges:

“COUNSEL ADDRESSED ON VOIR DIRE

HIS HONOUR: Yes very well thank you I think the evidence should be limited so that there is merely an expression of opinion as to the scientific view; that the testing does not exclude the possibility of paternity. So the evidence of likelihood and certainly the evidence as to percentage should be exluded.

CROWN PROSECUTOR: If your Honour pleases in that event --

HIS HONOUR: And I say that because I think there is a very considerable risk that the jury notwithstanding any blandishments on my part may take the practical position of a punter and say this is not just a mere certainty but an absolute certainty. Anyway sorry I interrupted you.

CROWN PROSECUTOR: No your Honour. I know what it is your Honour is saying. Your Honour that being the case I would not call both experts, there seems little point in doing that and your Honour subject to anything my friend might have to say I would not go through the intricacies of the testing involved in coming to that conclusion but simply have the expert give the opinion on the basis of testing.

HIS HONOUR: Yes. You will accept I suppose the proposition put by Mr. Pontello that DNA testing is very good when it is a question of exclusion, it can exclude the possibility that someone was the sire and that ought to be explained to the jury.

CROWN PROSECUTOR: Yes your Honour but it’s certainly not finger printing. If your Honour would give me a moment to confer with my witnesses so that I can prepare them for that and then it will be very short evidence from that point onwards.”

66 In February 2000 G.K. was re-presented for trial in the District Court at Campbelltown and before Moore DCJ and a jury. He was so presented on an indictment containing eight counts. Seven of the counts reproduced the charges as to which the jury in the first trial had been unable to agree upon verdicts. There was an additional charge alleging the intimidation of a witness.

67 This second trial aborted after two days of hearing. The reasons are of no present moment.

68 Prior to the commencement of this second trial, further DNA testing had been carried out by each of two independent laboratories. The Crown sought to lead this evidence, and Moore DCJ granted an application by the defence for a voir dire hearing to determine the admissibility of the evidence. At the conclusion of this voir dire hearing, and on 8 February 2000, Moore DCJ published two judgments. In the first judgment his Honour considered whether, and if so to what extent, he was bound by the earlier ruling of Ford DCJ. The conclusions to which his Honour came in that connection depended substantially upon a careful analysis by his Honour of the decision of the High Court of Australia in Rogers v The Queen (1994) 181 CLR 251; and of the decision of the Court of Appeal of Victoria in Edwards (1997) 94 A Crim R 204. His Honour’s conclusions are expressed succinctly in paragraphs 26 and 27 of the published judgment. Those paragraphs read:

“26. The ratio in

Rogers

has two strands - (1) the ruling in the original trial must be conclusive and (2) the importance of avoiding the scandal of conflicting decisions. It is cloaked by the special shroud of the distinct nature of criminal proceedings, with its fundamental principles (see

Rogers

per Deane and Gaudron JJ quoted above)

27. My analysis of the application of

Rogers

, and as to the authority of

Edwards

in the present case, is to say that I should pay full deference to the ruling of his Honour Judge Ford unless (a) his Honour’s finding was clearly wrong, or (b) there are different circumstances in the application of the discretion in the present case, or there is fresh evidence in the present case, in either of those two circumstances being such as would require a real re-determination of whether the discretion should be exercised.”

69 Moore DCJ then heard further submissions from counsel; and thereafter published the second of the two judgments to which I earlier referred. His Honour described as follows his then task as his Honour perceived it:

“I have to determine whether the exercise of the discretion by his Honour was clearly wrong, or that the circumstances prevailing at this trial are sufficiently different, or that there would be an admission of fresh evidence of a sufficiently different nature, to warrant a fresh consideration of whether or not I should exercise the discretion.”

70 His Honour then dealt with each of the elements identified in that definition of his task, and came ultimately to the following conclusion:

“I feel that the legal principles require me not to disturb the exercise of the discretion from that which was exercised by his Honour Judge Ford and I would therefore direct that the Crown is entitled to lead evidence that DNA testing was done which shows that the accused could be the father but that there should not be the arithmetical figures put before the jury.”

71 In due course, and in connection with the third of the questions now submitted by the Director to this Court, it will be necessary to consider his Honour’s reasoning and conclusions in the first of the two judgments. It will be, similarly, necessary to return in due course, and in connection with the second of the submitted questions, to the reasoning and conclusions expressed in his Honour’s second judgment.

72 As I have earlier noted, this second trial of G.K. aborted. Subsequently, and on 20 March 2000, G.K. was indicted for the third time, and again before Moore DCJ, the indictment containing the same counts as had been contained in the indictment presented in connection with the second, and aborted, trial. The rulings which Moore DCJ had given during the course of the second trial were treated as continuing in connection with the third trial. On 22 March, and after his Honour had given the jury a direction of the kind described and explained by the South Australian Court of Criminal Appeal in Reg. v Prasad (1979) 23 SASR 161, the jury returned verdicts of not guilty upon all eight of the counts in the indictment.

73 Against the whole of the foregoing background, the Director has now submitted for determination by this Court the following two question:

“1. Where a trial Judge makes a discretionary ruling on the admissibility of certain evidence is a trial Judge at a subsequent trial following a failure by the first jury to agree on its verdict bound to follow that ruling with respect to the admissibility of the same evidence?

2. Was his Honour Judge Moore in error in refusing to admit evidence of the probability, in numerical terms derived from DNA testing, that

was the father of the complainant’s child, on the basis that there was a real risk of unfair prejudice to the accused?”

: I am of the opinion that the decisions, previously herein mentioned, of Rogers and of Edwards, support the following propositions:

[1] A Judge who is asked to exclude evidence pursuant to s 137 of the Evidence Act is not required to exercise any discretion such as is required, for example, by a decision whether evidence should be excluded pursuant to s 135 of that Act. The Judge is required, rather, to make a connected series of findings of law and of fact upon which s 137 will operate without any further discretionary input of the Judge.

[2] That connected series of findings will derive from the following connected series of questions:

2.1 Is the tendered evidence relevant at all in the sense required by s 55(1) of the Act? If not, then the evidence is in any event inadmissible.

2.2 If the tendered evidence is relevant in that sense, then what is its probative value, as that expression is defined in the Dictionary that forms part of the Act?

2.3 Is there a danger that the tendered evidence, if admitted, will give rise to the danger of unfair prejudice to the defendant: that is, to the real risk that the evidence, if admitted, will be misused by the jury in some way that is unfair to the defendant?

2.4 If so, then where does the preponderant weight lie as between, on the one hand that probative value; and on the other hand that danger of unfair prejudice to the defendant?

If the preponderant weight favours the factor of probative value, then s 137 does not require the exclusion of the evidence; and the evidence ought to be admitted unless there is some other proper basis for its exclusion.

[3] The answering of each of the foregoing four questions does not depend upon any discretionary judgment, still less any merely intuitive response. It depends upon the reaching of a rational conclusion drawn from facts admitted or proved.

[4] A particular ruling that some tendered piece of evidence either is, or is not, required by the operation of s 137 of the Evidence Act to be excluded can be re-visited by the trial Judge at any time until the Crown and the accused have finally closed their respective cases.

[5] Thereafter, when the jury has returned a verdict, the particular evidentiary ruling is final as between the Crown and the accused for as long as the verdict remains on foot.

[6] Should the verdict be set aside on appeal, then as Batt JA put the point in Edwards : “the whole slate ……. (is) …….wiped clean ” . One consequence of that will be that in the event of a re-trial, the Judge presiding at the re-trial will not be bound to adopt the ruling given in the earlier trial, for the issues of law and of fact determined in the earlier trial in connection with the ruling will be at large, the verdict which previously gave them finality having no continuing legal effect. In my opinion the same result must follow in a case where the jury at the earlier trial did not reach a verdict at all.

[7] The proposition [5] above is subject to the qualification that in any subsequent trial of the particular accused, the evidentiary ruling will not bind the subsequent trial Judge:

(a) If it is shown that the ruling was in some way tainted by fraud; or

75 As has been earlier noted, Moore DCJ proceeded upon the basis of two stated criteria.

76 As to the criterion stated in paragraph 27(b) of his Honour’s reasons, I would respectfully agree in general with what is said by his Honour, but subject to two matters:

1. The reference to a “discretion” is, in my respectful opinion, misconceived in a case where it is the proper application of s 137 of the Evidence Act that is in point; and

“pay (ing) full deference”

“should follow”

77 As to the criterion stated in paragraph 27(a) of his Honour’s reasons, I respectfully disagree with his Honour to the extent necessary in order to maintain the propositions numbered 1 through 7 as previously herein stated. Even if the Judge in the relevant subsequent trial thinks that the ruling in the relevant earlier trial is “clearly wrong”, I think that the better view is that the earlier ruling should be, nevertheless, followed if there is no proper basis for distinguishing it; if the earlier trial has resulted in a verdict that has not been set aside on appeal; and if, therefore, a refusal to follow the earlier ruling would have the practical result described by Brennan J in Rogers as that of “(promoting) the notion that a criminal trial is, in significant respects, a lottery”.

78 The present discussion has concentrated upon the position arising when the basis upon which the admission of evidence is challenged is that the correct application of s 137 of the Evidence Act requires that the evidence not be admitted. That was, plainly, the type of challenge with which Moore DCJ understood himself to be dealing.

79 It is equally plain that the issue debated before Moore DCJ was argued out upon the basis of a common assumption that Ford DCJ, also, had given a s 137 ruling; that is to say, a ruling not entailing the exercise of any residual discretion.

80 The point has some present significance because of the express reference in the question submitted to this Court to “a discretionary ruling on the admissibility of certain evidence”, (emphasis added). In the events that actually happened, the question would have been more relevantly introduced by some such words as: “……………….excludes evidence upon the basis of the application of s 137 of the Evidence Act”.

81 Since the question as actually raised refers to “a discretionary ruling”, it is, in my opinion, expedient to consider whether the propositions numbered 1 through 7 and earlier herein advanced would need revision in a case where the earlier ruling was a true discretionary ruling, as, for example, a ruling based upon s 135 of the Evidence Act.

82 In my opinion there is no such need. There is nothing talismanic about the description “discretionary” as applied to, relevantly, an evidentiary ruling. “Discretionary” in that context does not imply some process that is peremptory or merely idiosyncratic. It implies a process of reasoning based upon facts admitted or proved. If a trial in which a discretion is given a reasoned exercise issues in an unreversed verdict, then I do not see why the reasoning which supports the stated propositions numbered 1 through 7 above in the case of a non-discretionary ruling, should be any less applicable in the case of a discretionary ruling.

83 For the whole of the foregoing reasons, I would answer the first submitted question: no.

: it is convenient to begin by noting the salient features of the relevant expert evidence that was placed before Moore DCJ.

85 The Crown called Mr. Robert Goetz and Dr. Peter Gunn.

86 Mr. Goetz described himself as a forensic biologist employed at the Division of Analytical Laboratories at Lidcombe. His academic qualifications were those of a Bachelor of Science with Honours from the University of New South Wales. He said that he had been a forensic biologist since 1975; and that he had been concerned with DNA testing since about 1989. His qualifications to give opinion evidence about DNA testing in general, and about the results of such testing in G.K’s particular case, were not the subject of defence challenge.

87 Dr. Gunn described himself as a scientist and a director of a company named Silbase Scientific Services, being a company engaged in DNA testing, particularly DNA parentage testing. He gave his academic qualifications as being those of a Bachelor of Science with Honours from Flinders University in South Australia; and a Doctor of Philosophy awarded by the University of Adelaide in 1982. He said that he had studied statistics as part of his under-graduate science degree, and that he had been using statistics in his professional career almost daily since the time of those studies. His qualifications to give expert opinion evidence, also, were not the subject of defence challenge.

88 Mr. Goetz, in his evidence in chief, confirmed and explained DNA testing results of G.K., which results had been incorporated into a written report earlier provided by him to the Crown. Mr. Goetz said that the results showed that G.K. “could be the biological father” of C. He said that the statistical analysis of the results could be expressed as follows:

“Paternity Index: 220,000:1

Relative Chance of Paternity = 99.9995%”

89 Mr. Goetz explained the import of the Paternity Index as thus recorded as being that “…………….it is 220,000: [sic, but I infer that the word “times” is missing and ought to be inserted] - more likely that [G.K] is the biological father of [C] than anybody else taken at random in the population”. He explained that the expressed relative chance of paternity is “a value which is really related to the paternity index. It’s a re-calculation of the paternity index. However, I’d prefer to stay with the paternity index. I think it’s easier to understand”.

90 Mr. Goetz gave evidence in chief, and was subsequently cross-examined closely, about the statistical validity of the general population genetics data bases used by him in connection with his DNA testing of and in connection with G.K. It is not necessary to recapitulate the fine detail of that evidence.

91 Dr. Gunn, too, gave evidence in chief confirming the contents of a written report earlier provided by him to the Crown. In Dr. Gunn’s case his conclusion was expressed in terms that G.K. “is not excluded from identification as the father of [C]”. Dr. Gunn expressed as follows the statistical representations of his results:

“Paternity Index 147,005 to 1

Relative Chance of Paternity = 99.9993%”

92 Dr. Gunn, explaining in chief the import of these statistical representations, gave the following evidence:

“Q. Just for the sake of completeness could you explain what is meant by Paternity Index?

A. Yes, the Paternity Index is a way of estimating the strength of the evidence from any particular genetic locus examined. For example on page 2A the first locus looked at, CSF1PO, we can tell that the child must have inherited the gene designated number ten from its biological father. There are two explanations for the result, either

really is the father of the child or just by coincidence he also has the 10 characteristics. The Paternity Index is a way of weighting those two possibilities. In that particular example it’s about 1.99 times more likely that he would - that he is the biological father than that he just has that characteristic by coincidence. The same logic is applied to all of those 12 tests and then the final figure, the Paternity Index, is the combination of those 12 --

Q. Multiplied --

A. -- multiplied together, yes.

Q. That is known as the product rule?

A. Yes.

Q. The Paternity Index that you came to when you did your testing in your report on September 11 1998 was what?

A. The Paternity Index was 147,005 to 1.

Q. And the relative chance of paternity?

A. Yes, the relevant chance of paternity, which is really expressing that index as a percentage, was 99.9993 per cent.

Q. In your experience they are high results?

A. They are high, they’re not unusually high for DNA testing but they are high results.”

93 Dr. Gunn, also, gave evidence in chief, and was subsequently cross-examined closely about, the statistical validity of the general population genetics data bases which he had used in connection with the testing of which he had given evidence. Once again, I do not think that it is necessary to canvass the fine detail of that evidence.

94 Because of the conclusion to which his Honour had come in connection with the subject matter of the first of the questions now submitted to this Court, Moore DCJ really did not engage with the principles applicable to the second question in the form in which that question is now submitted for the determination of this Court. In that particular sense, it would be possible now to deal with the second submitted question by answering it: yes, in that his Honour’s approach was flawed by reason of its incorrect dependence upon the earlier approach of Ford DCJ. It seems to me, however, that the proper course for this Court now to follow is to take up the real substance of the second question now submitted for the Court’s determination.

95 In that connection, I think that a useful starting point is the following passage taken from the judgment of King CJ, (Mitchell and Mohr JJ concurring), in Duke (1979) 1 A Crim R 39 at 41:

“Is the fact that the evidence includes scientific opinion as to the significance of the physical evidence capable of creating prejudice which could lead to the exclusion of the evidence? I would not wish to say anything which might be thought to limit a trial judge’s discretion, which is so necessary to the discharge of his overall duty to secure a fair trial. There may be unusual cases in which the judge has reason to fear that the jury will be overawed by the scientific garb in which the evidence is presented and will attach greater weight than it is capable of bearing. It is to be remembered, however, that under our system, whatever criticisms of it there might be, the assessment of the weight to be attached to expert evidence, as to other evidence, is the function of the jury. That being the system, a trial judge must assume, in my view, that the jury is capable of understanding that it is not bound to accept the expert evidence, that it is capable of resolving conflicts of opinion amongst the expert witnesses and that it will not be overawed by the scientific garb in which the evidence is presented to it. It is to be remembered, moreover, that for the purpose of enabling the judge to decide as to the exercise of his discretion the question of weight is to be judged upon the evidence which the prosecution proposes to present. It is not the function of the trial judge to hear conflicting expert evidence as to the significance of the physical evidence in order to determine for himself the disputed scientific issues. To do so would be to usurp the function of the jury.”

96 In seeking to apply those principles to the given facts of the present case, I have considered the expositions of principle which are to be found in the decision of this Court, (Hunt CJ at CL, Abadee and Hidden JJ), in Pantoja (1996) 88 A Crim R 554; and in the decision of Bleby J of the Supreme Court of South Australia in Humphrey (1999) 103 A Crim R 434. I read those authorities as supporting the following propositions:

[1] “DNA testing has been accepted by the courts for some years as an acceptable scientific technique for the identification of the source of bodily tissues, in accordance with the approach to scientific evidence generally adopted by this Court in Gilmore ”. [Hunt CJ at CL at 88 A Crim R, 558]

[2] There is, at least as a general rule, nothing so inherently difficult, confusing or misleading about properly qualified expert opinion evidence about DNA testing, either in general or in a particular case, as would justify a perception that a jury, acting reasonably and with the assistance of correct and appropriate directions from the presiding Judge, cannot be entrusted safely with the assessment of that opinion evidence. In this connection there is no necessary difference in principle between a case where there is no conflict in the expert opinion evidence, and a case where there is such conflict in the expert opinion evidence.

“The significance of a match between the blood type or DNA of the offender and the suspect (or accused person) must be clearly explained to the jury: that (as I said earlier) it establishes no more than that the accused

could

be the offender, whereas any blood test which positively excludes the accused as the offender -

if there is a reasonable possibility that the test is correct

- must necessarily exclude the accused completely notwithstanding that there is a match obtained by other blood tests which operate quite differently or independently, and however strong the other evidence in the case may be.” (emphasis taken from the text of the report]

Hunt CJ at CL notes specifically in footnote 22 on page 564 that his Honour has: “…………….assumed that the Crown had to establish beyond reasonable doubt that the [accused person] was not excluded as the suspect, and that the probability of the match having occurred by chance or coincidence is very small” .

[4} Where, at a particular trial, proposed opinion evidence of DNA testing is challenged as to its admissibility, a correct ruling upon the objection will depend upon: (a) the precise basis of the challenge, in the sense of identifying precisely whether the challenge depends upon a non-discretionary result arising from the balancing of particular findings of fact, as in a case depending upon, for example, s 137 of the Evidence Act ; or depends, rather, upon the exercise of a residual discretion, as in a case depending upon, for example, s 135 of that Act; and (b) the precise testing step that is being challenged.

[5] If the challenge is based upon such a provision as s 137, and if the challenge is aimed at the match results, rather than at their statistical interpretation, then: (a) the probative value of properly qualified opinion evidence will be substantial, because the current stance of the Courts is that such evidence of scientific matching is, as Hunt CJ at CL says: “an acceptable scientific technique” ; and (b) the existence at all of the real risk of unfair prejudice, in the requisite legal sense, and the proper comparative weighting to be given to any such risk found as a fact to exist, must take into account the propositions numbered [2] and [3] above.

[6] If the challenge is based upon such a provision as s 137, and if the challenge is aimed, not at the match results as such, but at their statistical interpretation, then both the question of probative value, and the question of the existence and proper weighting of any danger of unfair prejudice, must be decided in the light of the available evidence as to the sufficiency of the statistical validity of the data base(s) upon which the validity of the proposed statistical interpretation itself necessarily depends. The relevant onus of proof rests upon the Crown; and it is for the Crown to ensure that there is placed before the Judge whose ruling is being sought, sufficient and properly qualified evidence going to that issue of sufficiency of the statistical validity of the data base(s).

[7] If the challenge is based upon such a provision as s 135, and is aimed at the match results as such, then what is said in the proposition numbered [5] will apply, mutatis mutandis , both to the making of the necessary findings of fact upon the basis of which the residual discretion is to be exercised; and to the ultimate exercise of the discretion itself.

mutatis mutandis

97 It is, obviously, the case that Moore DCJ did not analyse in the foregoing way the particular evidence placed before his Honour. In my opinion, however, the application of the foregoing propositions to that evidence would confirm the correctness of his Honour’s ruling that the scientific opinion evidence that G.K. could be C’s father ought to be admitted.

98 As to the statistical interpretations, I would myself have thought that correct principle correctly applied justified the admission of at least so much of the statistical material as quantified the Paternity Index. The scientific opinion evidence seems to me to have demonstrated the sufficiency in that connection of the reliability of the relevant data bases; and to have explained the notion of the Index in a way that a reasonable and reasoning jury, properly directed, could readily enough have assessed properly.

99 I am more ambivalent about the percentage quantifications of the Relative Chance of Paternity. Mr. Goetz himself volunteered that he thought that the Paternity Index was the easier of the two statistical measures to understand, and I myself agree with that view. The bare percentage figures are so extraordinarily close to 100 per cent that there must be, at least, a real risk that jurors, even sensible jurors properly directed, would think that the difference between the percentage figures and 100 per cent was so miniscule that there could be no possibility that G.K. was not the father; when it is scientifically uncontroversial that the one thing that DNA testing cannot do is to exclude absolutely any possibility, however statistically trifling, to the contrary.

100 I infer from what Hunt CJ at CL says at the foot of 88 A Crim R, 561 and the following sentences on 562, that his Honour would have resolved the problem by reference to the demonstrated statistical validity of the given data base(s). I respectfully agree with that approach; and it would have led me, in the present case, to have excluded the raw percentage figures, whether upon the basis of s 137 or of s 135, not because of a fundamental dissatisfaction with the statistical sufficiency of the relevant data bases, but because of the combined effect of the considerations:

[1] that the residual risk of unfairness deriving from the subliminal impact of the raw percentage figures would have been, to me, both real and unacceptable; and

101 Accordingly, I would answer the second question in the form now submitted to this Court: yes as to the Paternity Index statistics; no as to the Relative Chance of Paternity statistics.

I have read the judgment in draft form of Mason P and Sully J. I agree with the judgment of Mason P and Sully on question one and their reasons therefore.

103 I agree with the orders proposed by Sully J on question 2 for the reasons enunciated by Mason P.

*****************

Citations

R v GK [2001] NSWCCA 413

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CITATION:	REGINA v GK [2001] NSWCCA 413
FILE NUMBER(S):	CCA 60738/00
HEARING DATE(S):	1 May 2001
JUDGMENT DATE:	16 October 2001
PARTIES :	REGINA v GK
JUDGMENT OF:	Mason P at 1; Sully J at 62; Dowd J at 102

LOWER COURT JURISDICTION:	District Court
LOWER COURT FILE NUMBER(S) :	99/21/3063
LOWER COURT JUDICIAL OFFICER :	Moore DCJ

COUNSEL :	Crown: R D Ellis Respondent: P Byrne SC/M A Marty
SOLICITORS:	Crown: S E O'Connor Respondent: Greg Walsh & Co
CATCHWORDS:	Evidence - whether judge at subsequent trial required to follow ruling of prior judge on admissibility of evidence - s137 Evidence Act 1995 - whether trial Judge should have allowed numerical probability evidence derived from DNA testing to go to jury - paternity index - relative chance of paternity statistics - Bayes' Theorem - whether probative value outweighed by risk of unfair prejudice - "prosecutor's fallacy". (D)
CASES CITED:	Annot 84 ALR 4th 313 Arnotts v Trade Practices Commission (1990) 24 FCR 313 Burger King Corporation v Hungry Jack's Pty Ltd [2001] NSWCA 187 Chamberlain v The Queen (No 2) (1984) 153 CLR 521 Doheny and Adams [1997] 1 Cr App R 369 Duke (1979) 22 SASR 46; 1 A Crim R 39 Gibson v R [2001] TASSC 59 Hassett [1999] EWCA Crim 1481 HG v The Queen (1919) 197 CLR 414 Humphrey (1999) 103 A Crim R 434 Latcha (1998) 104 A Crim R 390 Makita (Australia) Pty Ltd v Sprowles [2001] NSWCA 305 Milat (1996) 87 A Crim R 446 Mitchell (1997) 98 A Crim R 32 Ordukaya v Hicks [2000] NSWCA 180 Pantoja (1996) 88 A Crim R 554 Papakosmas v The Queen (1999) 196 CLR 297 People v Leonard (1997, 569 NW 2d 663, appeal denied 570 NW 2d 659) Perry v The Queen (1982) 150 CLR 580 R v Denis Adams (No 2) [1998] 1 Cr App R 377 R v BD (1997) 94 A Crim R 131 R v Edwards (1997) 94 A Crim R 204 R v Karger [2001] SASC 64 R v Gallagher [2001] NSWSC 462 R v Jarrett (1994) 62 SASR 443 R v Kami (District Court of New South Wales 14 May 2001) R v Noll [1999] VSCA 164 Reg. v Prasad (1979) 23 SASR 161 Rogers v The Queen (1994) 181 CLR 251 State v Freeman (1997, 571 NW 2d 276) State Government Insurance Commission v Laube (1984) 37 SASR 31 State of Nebraska v Champ (20 March 2001, No A-00-617) State v Carter 524 NW 2d 763 Steffen v Ruban [1966] 2 NSWR 622 Toki (2000) 116 A Crim R 536 United States v Davis (1994, 40 F 3d 1069, cert den (US) 131 L Ed 2d 239)
DECISION:	Question 1. Where a trial Judge makes a discretionary ruling on the admissibility of certain evidence is a trial Judge at a subsequent trial following a failure by the first jury to agree on its verdict bound to follow that ruling with respect to the admissibility of the same evidence?; Answer: No.; Question 2. Was his Honour Judge Moore in error in refusing to admit evidence of the probability, in numerical terms derived from DNA testing, that …..(GK)…… was the father of the complainant's child, on the basis that there was a real risk of unfair prejudice to the accused?; Answer: Yes as to Paternity Index Statistics; No as to Relative Chance of Paternity Statistics.