R v D G; D G v The Queen [2010] VSCA 173

2 The background facts were as follows. A small quantity of DNA was detected on a man's thong which was found close by the body of the female victim. The body was discovered some 500 metres or so from the accused's home. The Crown case was that the DNA was that of the accused. The defence objected to the admissibility of that evidence. After a lengthy voir dire the trial judge ruled in favour of the Crown.

3 The body of the deceased was found wrapped in black plastic. A second small quantity of DNA was detected on a nylon rope that had been used to tie up the body. Once again, the Crown case was that the DNA was that of the accused. In relation to this matter, however, his Honour ruled that the evidence should not be led.

4 The Crown case was largely circumstantial. The DNA evidence, if accepted, linked the accused to the body of the deceased. As such, it established a connection between the accused and the disposal of the body, and thereby strengthened the circumstantial case.

5 Both the accused, and the Crown, were dissatisfied with his Honour's rulings. The defence sought to challenge the decision to admit the evidence of the DNA found on the thong, while the Crown sought to challenge the decision to exclude the evidence of the DNA detected on the nylon rope. Each side opposed the other's application for leave.

6 We indicated, at the conclusion of the hearing, that we would publish our reasons for refusing leave to appeal, in both matters, at a later time. Those reasons are as follows.

7 Plainly, each ruling constituted an 'interlocutory decision' concerning the admissibility of evidence. The trial judge certified, pursuant to s 295(3) of the Criminal Procedure Act 2009 (Vic) ('the Act'), in relation to both rulings, that 'the evidence, if ruled inadmissible, would eliminate or substantially weaken the prosecution case'. However, the transcript reveals that the Crown sought such certification in relation to the DNA on the nylon rope only as a precaution against this Court setting aside his Honour's ruling as to the DNA found on the thong. Senior counsel for the Crown frankly conceded that, if the ruling regarding the thong stood, he would not press for leave to appeal in relation to the nylon rope.

8 The Crown's position was understandable, as was his Honour's decision to certify in relation to the nylon rope. As is apparent from the transcript, he took the view that, if the admissibility of the evidence regarding the DNA on the thong was to be considered by this Court, it would be sensible to have the matter of the DNA on the nylon rope before the Court as well.

9 That said, in our view, the formal requirements for certification under s 295(3)(a) were not met in relation to the nylon rope. That evidence had been excluded, but other arguably more potent evidence of DNA had been ruled admissible. It could not be said that the evidence regarding the DNA on the nylon rope, which had been excluded, satisfied the statutory criterion for certification, namely that 'if [that evidence were] ruled inadmissible, [it] would eliminate or substantially weaken the prosecution case'.

10 Of course, that criterion might, at a later stage, be met, but only if this Court allowed the appeal in relation to the DNA on the thong. Then, and only then, would there be a statutory basis for certification regarding the nylon rope. His Honour's decision to certify in relation to the nylon rope was, nonetheless, understandable.

11 Certification was not in issue in either application before this Court. Rather, the question to be determined was first, whether to give leave in relation to those applications and, next, assuming leave were given, whether to allow the particular appeal.

12 The criteria for the giving of leave to appeal against an interlocutory decision in a criminal trial are set out in s 297 of the Act. That section provides as follows:

(1) Subject to subsection (2), the Court of Appeal may give leave to appeal against an interlocutory decision only if the court is satisfied that it is in the interests of justice to do so, having regard to -

(a) the extent of any disruption or delay to the trial process that may arise if leave is given; and

(b) whether the determination of the appeal against the interlocutory decision may -

(i) render the trial unnecessary; or

(ii) substantially reduce the time required for the trial; or

(iii) resolve an issue of law, evidence or procedure that is necessary for the proper conduct of the trial; or

(iv) reduce the likelihood of a successful appeal against conviction in the event that the accused is convicted at trial; and

(c) any other matter that the court considers relevant.

(2) The Court of Appeal must not give leave to appeal after the trial has commenced, unless the reasons for doing so clearly outweigh any disruption to the trial.

(3) If the Court of Appeal refuses leave to appeal under this section, the refusal does not preclude any other appeal on the issue that was the subject of the proposed appeal.

13 The overarching test to be applied in determining whether to give leave is whether it is 'in the interests of justice to do so'. As can be seen from s 297, the legislature has sought to provide some guidance as to the meaning to be given to that expression in the particular context in which it is used.

14 So far as the present matters are concerned, it was common ground that there would be no significant disruption or delay to the trial process if leave to appeal were given. No jury has yet been empanelled. Accordingly, s 297(1)(a) presented no impediment to the giving of leave.

15 In answer to questions put to him by the Court, senior counsel for the Crown indicated that, were the DNA evidence to be excluded in its entirety, the trial would still proceed. He acknowledged that, in that event, the case against the accused would be considerably weakened, but maintained that there would still be sufficient evidence available to justify continuing with the prosecution. Accordingly, the specific justification for the giving of leave set out in s 297(1)(b)(i), namely, that the determination of the appeal against the interlocutory decision might render the trial unnecessary, is not available in this case.

16 The same can be said of s 297(1)(b)(ii). Again, in answer to questions from the Court, senior counsel for the Crown indicated that the exclusion of the DNA evidence would not 'substantially reduce the time required for the trial'. Counsel for the accused did not challenge that assertion.

17 The language of s 297(1)(b)(iii) presents some difficulties. The problem lies in the meaning to be accorded to the expression 'necessary for the proper conduct of the trial'. The word 'necessary' suggests a high degree of need, and is ordinarily synonymous with 'essential'. It connotes something more than merely 'useful', or 'important'. There are also problems with the expression, 'the proper conduct of the trial'. In one sense, any ruling on a point of evidence that is even arguably erroneous could be said to justify the giving of leave to appeal on the basis that to allow the evidence to be led would be 'be inconsistent with such proper conduct'. Plainly, however, the legislature could not have intended the phrase to be read so widely. Otherwise, s 297(1)(b)(iii) would not act as any sort of filter in determining whether leave to appeal should be given.

18 Finally, turning to s 297(1)(b)(iv), it is obvious that, were this Court to allow the appeal against his Honour's decision to admit the DNA found on the thong, that would 'reduce the likelihood of a successful appeal ... in the event that the accused is convicted at trial'. However, that would be so in almost every case in which a challenge by an accused person to an adverse ruling on a point of evidence were to succeed. By allowing an interlocutory appeal in any such case, the Court would, of necessity, be reducing the scope for a subsequent successful appeal. After all, the ground upon which the interlocutory appeal had succeeded would thereafter be moot.

19 The final matter to which the Court may have regard, when determining whether or not to give leave, is set out in s 297(1)(c). It provides, somewhat uninformatively, that the Court may have regard to 'any other matter that the court considers relevant'.

20 Interlocutory appeals in criminal matters in this State were introduced by the Act, which applies to all criminal proceedings commenced after 1 January 2010. There have since been a number of such appeals, including some which have succeeded. This Court has begun to develop a body of case law which will govern the giving of leave to appeal.

21 In McDonald v DPP,[1] an application for leave to appeal was brought against a trial judge's refusal to quash a presentment. The basis upon which the challenge was mounted was that the applicant, an indigenous man, was not amenable to the provisions of the Drugs, Poisons and Controlled Substances Act 1981 (Vic), because he was subject only to Aboriginal law. The trial judge had certified, pursuant to s 295(3)(b) of the Act, that the interlocutory decision was of 'sufficient importance to the trial to justify it being determined on an interlocutory appeal'.

22 Not surprisingly, leave to appeal was refused. The arguments sought to be advanced on behalf of the applicant were described by Ashley JA as 'hopeless in law'.[2] Accordingly, the interests of justice would not be served by agitating a point, the inevitable resolution of which would neither render the trial unnecessary, nor achieve any other useful object.

23 Redlich JA went even further. His Honour added that certification should not necessarily be granted, even if the point at issue was not absolutely hopeless, and the trial judge considered that the interlocutory decision might be attended by some doubt.[3] In other words, in his Honour's view, the mere fact that a point might be arguable did not mean that a judge should grant certification. Plainly, his Honour had in mind that the giving of leave by this Court, which is discretionary, should be dependent, in part, upon the strength of the argument in support of the appeal. In accordance with the principles developed in relation to the giving of leave in interlocutory matters in civil proceedings, the merits were to be taken into account.[4]

24 Redlich JA's approach in McDonald was considered, and adopted, by this Court in Wells v The Queen.[5] The case involved an application for review of a decision refusing to certify under s 295(3)(b). The application for review was dismissed essentially because there was little merit in the proposed challenge to the interlocutory decision.

25 Interlocutory appeals in criminal matters have been available in New South Wales for some years. Section 5F of the Criminal Appeal Act 1912 (NSW) provides for such appeals. Ordinarily, and unlike the position in this State, they are restricted to an 'interlocutory judgment or order'. However, so far as the Crown is concerned, s 5F(3A) extends the ambit of such appeals to 'any decision or ruling on the admissibility of evidence'. Jurisdiction to entertain such an appeal exists only if the 'decision or ruling eliminates or substantially weakens the prosecution's case'.

26 The case law in New South Wales is relevant to the approach that should be taken by this Court on an application for leave to appeal against an interlocutory decision. The authorities suggest that the New South Wales Court of Criminal Appeal is cautious in its approach to such appeals.

27 In R v Shamouil,[6] the Crown appealed against a ruling made by a judge during the course of a trial excluding evidence of a photo identification of the accused. Spigelman CJ, with whom Simpson and Adams JJ agreed, observed that s 5F(2), which had been repealed and replaced by s 5F(3A), had been interpreted so as not to extend to rulings which merely weakened, but did not destroy, the Crown case. Section 5F(3A) was intended to remedy that situation by broadening the scope for Crown appeals against interlocutory rulings to include those that 'substantially weakened' the prosecution case.

28 Despite the introduction of s 5F(3A), and the clear manifestation of legislative intent that it displayed, Spigelman CJ observed that the jurisdictional issue posed by that section was 'not intended to involve an inquiry into the weight to be given to the evidence excluded'.[7] In his Honour's terms, questions of weight were for the jury, and not for the Court of Criminal Appeal.[8]

29 The introduction of interlocutory appeals in criminal matters represents a radical departure from well established, and authoritative, doctrine. The High Court has repeatedly spoken about the undesirability of 'fragmentation' of the criminal process.[9] Interlocutory appeals involve just such 'fragmentation'. The legislature in this State has taken the view that this is a price worth paying.

30 There are, no doubt, cases where such 'fragmentation' can be justified. A swift and dispositive ruling by this Court on a point of law that is critical to a trial may render that trial unnecessary, or significantly reduce its length. As previously indicated, the Court has already allowed a number of interlocutory appeals this year.

31 At the same time, it must be borne in mind that the legislature has chosen not to confer a right of appeal in relation to interlocutory decisions in criminal trials. Rather, there are dual hurdles which must be overcome before this Court will entertain an appeal against such decisions. First, there must be either certification, or a successful review against a refusal to certify. Secondly, the Court itself must be satisfied that leave to appeal is warranted.

32 Rulings on points of evidence can be particularly problematic when viewed as suitable vehicles for interlocutory appeals. The legislature has itself recognised that fact. The criteria for certification in s 295 are different when it comes to rulings on evidence than they are in relation to other interlocutory decisions.

33 Evidentiary rulings are both commonplace, and numerous. They are routinely made in almost every trial conducted in this State. Many, if not most, such rulings are important. If a ruling is made in favour of the Crown, the prospects of conviction are enhanced. If the ruling goes against the Crown, those prospects are reduced.

34 There are real dangers if interlocutory appeals against rulings of that kind are too readily brought before this Court. That is particularly so if those rulings turn, in part, upon matters of weight as assessed by a trial judge. These are qualitatively different from rulings on what might be termed 'pure points of law'. There is also a difference between a challenge to legal admissibility, and a challenge based upon the exercise of judicial discretion. An appeal against a decision as to legal admissibility is likely to provide guidance of a more general nature than an appeal against the manner in which a trial judge has balanced the various factors relevant to the exercise of judicial discretion.

35 As we have said, the overarching principle which governs the giving of leave to appeal is 'the interests of justice'. In that context, there were several factors that militated against giving leave to appeal in a matter such as that involving the DNA detected on the thong.

36 First, it was not submitted before us that this evidence was inadmissible as a matter of law.[10] Rather, it was submitted that it ought to have been excluded in the exercise of judicial discretion under s 135 of the Evidence Act 2008 (Vic) or, alternatively, by virtue of the balancing process required under s 137 of that Act.

37 Counsel for the accused was invited to point to any specific error on the part of the trial judge in his formulation of the relevant legal principles. It is fair to say that he found it difficult to do so. He submitted only that his Honour had erred when dealing with the test to be applied when exercising the discretion under s 135, or considering whether the danger of unfair prejudice outweighed the probative value of the evidence under s 137, in the context of an asserted possibility that the DNA on the thong may somehow have been contaminated.

38 To understand that submission, it is necessary to set out in some detail various passages from his Honour's ruling regarding the application to exclude that evidence. After initially rejecting the contention that the evidence was irrelevant, his Honour turned to what he described as 'the contamination argument'. He dealt with that argument at considerable length. In his ruling, he said:

1. Mr Chadwick contended that Item 11.1 was contaminated and thus of no probative worth. There is no doubt that the accused bears an onus in relation to the contamination issue, although I do not consider that it is as high as having to demonstrate actual contamination. It is sufficient, in my view, for the accused to prove that there is a real chance that Item 11.1 was contaminated either before or during the testing process. By "real chance" I mean more than a merely theoretical chance of contamination and one that is sufficiently high as to either eliminate or substantially erode the probative worth of the evidence. Should the accused prove that the probative worth is eliminated, the evidence is irrelevant and will be excluded. Should he demonstrate that its probative worth is substantially eroded, then its residual worth will need to be assessed against the unfair prejudice considerations as set out in s 137 and s 135 of the Act.
2. It is necessary to set out a summary of the testing process for Item 11.1. It was not until the sixth test of Item 11.1 that DNA was detected. This is because the sample was dirty and so the presence of "inhibitors" masked the presence of DNA. Five "cleanups" were conducted of the sample before results were found. Each test involved placing a tiny amount of the material extracted from Item 11.1 into a well on a plate. The plate contained ninety six wells, most of which received either standard solutions or material to be tested for DNA relating to a variety of cases. To load the wells, marked sealed tubes would be retrieved from a refrigerator. They would be arranged in a rack in the same formation as they were to be placed in the plate. Each tube would then individually be taken from the rack, opened, two microlitres would be removed from the tube using a "pipette" and placed in the appropriate well. Simultaneously the tube would be closed and placed back in the rack.

33. In substance, the accused points to the following:

(a) It is asserted that there is insufficient evidence before the court to explain where, how and with what other items Item 11.1 was stored before and between bouts of examination;

(b) The sample taken from Item 11.1 was initially very dirty, resulting in inhibitors masking the potential presence of DNA. Five separate "clean ups" were conducted and the product then tested for DNA before it was detected on the sixth test;

(c) During the fourth test (run 268) the 11.1 sample was tested as part of the same run as a covert sample of the accused's DNA. This, it is said, gives rise to the spectre of actual contamination between the samples;

(d) It is asserted by Dr McDonald that during the loading for tray 268, sample 11.1 was handled in such a way as allowed for contamination;

(e) The fact that the accused's DNA was found only after this 4th run is some evidence that contamination occurred during that 4th run or is at least consistent with that occurring;

(f) No confirmatory testing was done after the positive result from the 6th test. Given the level of allele peaks used by VPFSC, the accused argued that reproducibility was essential.

1. Evidence relating to the potential for contamination occupied a substantial proportion of all evidence adduced during the preliminary arguments. Ultimately, Dr McDonald conceded that if there were to be contamination, the most likely occasion upon which it could have arisen was during the loading of the plate for the fourth test. The plate contained 96 separate wells. Sixteen wells were loaded with standard solutions. Sixty seven wells were then loaded with various DNA samples for testing. Eleven further wells were then loaded with other substances, irrelevant for present purposes. The covert sample was the twelfth sample loaded in its well. It was loaded by using a pipette which was used to extract a tiny amount from the test tube in which the sample was stored. Ms Prince described the process by which samples of the DNA extract were loaded for quantitative testing:

the samples are stored in a specific fridge located in the DNA science area...

The samples that are listed on this sheet are the samples that have been added to the plate...

(In the fridge) the DNA extract is a liquid that's placed in a tube and the tube has specific labelling on it and these tubes are placed on a rack which is on a shelf...

When I've gone to pick up these samples, I've placed them (in a rack) in the order of the sample sheet...

Item 11.1 was extracted on 14 December 2007...

I'd go to the quantification rack based on what's on the sample sheet and position them into the rack according to what position I'd load them onto the plate...

First you set up the samples that require quantification in a rack in the order of where they will be loaded onto the plate...and then you would actually load those samples onto the...plate....

all transfer steps are witnessed by another analyst who is authorised ...to ensure that the correct samples are being loaded in the correct positions on the plate...

(The sample tubes) are always capped...

I'd then go and set up the 7500 plate. The setup is performed in an isolated area in its own separate hood. Prior to use of the hood it is decontaminated with hydrochloride...

I would set up the actual plate which is a sterile plastic plate which contains the 96 wells...

two microlitres (are) taken out of the tube and placed in the well....

only one tube is handled at any given time...I would open that tube. I would use the pipette which is the instrument used to measure volume and on top of the end of the pipette a tip is placed, which is a sterile tip and which is only used once...

I would take two microlitres from that tube. I would close that tube immediately and place it back into the rack and place the two microlitres of sample into the relevant position that it is required in...

1. Thus, Ms Prince described a process whereby each tube is sealed at the top, opened to extract a tiny amount for loading on the plate using the pipette and then closed immediately and replaced in its position on the "intermediate rack".
2. Any contamination as between wells on the plate is irrelevant for present purposes as the contents of every well tested were destroyed after testing, and the results of the testing for this run (as far as 11.1 was concerned), were negative, but with further clean ups suggested. Thus, the only potential for contamination during this testing process above and beyond the background risk in every laboratory is if, somehow, some of the contents of the tube containing extract from the covert sample (Item 28A-1) entered the tube containing the extract from Item 11.1.
3. As I have said, the covert sample was the twelfth sample loaded. The right thong sample (from Item 11.1) was the fifty eighth sample loaded. There were, therefore, forty five separate samples loaded between samples 28A-1 and sample 11.1. It follows that there were forty five separate tubes opened for a short time and then closed between Items 28-1 and 11.1 being opened and closed themselves. There is no evidence that any other item being tested during this run was contaminated by sample 28A.
4. Dr McDonald criticised the procedure of running a covert sample with an evidentiary sample in the same test. A covert sample is similar in nature to a reference sample in that it is demonstrably the product of a sample taken from a suspect. It should, therefore, be treated in the same way, he argued, as a reference sample and be kept completely isolated from any evidentiary samples such as 11.1. There is some force in this argument, but it avoids the ultimate question. On this occasion and in relation to these two samples, is there a real chance of contamination?
5. I have concluded that whilst it may be desirable (and I consider it is desirable) to isolate covert samples from evidentiary samples completely, there is no evidence to suggest that on this occasion there is a substantially elevated risk of contamination of Tube 11.1 with some of the contents of Tube 28A-1. Mr Chadwick pointed to Ms Prince's evidence that she wore the same laboratory coat for about a week and that she did not change her disposable gloves between each sample.
6. Ms Prince did state, however, that she changed her gloves frequently during the loading procedure and she thought it unlikely that she would be wearing the same gloves whilst loading the two relevant samples.
7. Mr Fowler's evidence on this aspect was, I consider, thoughtful and measured:

Given my assessment of the situation, and given that this particular run was the only instant in my opinion where there was a possible contamination event, I have considered that in reference to the other possibility which that DNA was present all along; with my knowledge [was] of this procedure and as I discussed earlier, about the no two tubes being open at the same time, and considering how many samples there were in between, I believe there is a very minimal opportunity for a contamination event to occur at this stage of the process, and given that is the only opportunity, in my opinion, for the contamination to have occurred, I do not believe that is the case. Whereas, in reference to all the clean-up attempts and the UD with asterisk, in my opinion that is just consistent with it being a very dirty sample that required many clean-ups and there may well have been DNA present all along. While I cannot give 100% assurance, as I never can, in my opinion, I feel it is likely the DNA was present all along.

1. In his written submissions, Mr Chadwick argued there was "insufficient evidence before the Court to explain where, how, and with what other items Item 11.1 (that is the physical thong itself) was stored between bouts of examination". The evidence is that it was only examined once for the purposes of swabbing for DNA material. No issue of any moment was made of the pre-examination storage conditions.
2. Mr Chadwick further argued that once DNA was detected after the sixth test, it should have been tested again. He relied on Dr McDonald's evidence to the effect that reproducibility equates to reliability. Ms Federle and Mr Fowler disagreed with Dr McDonald on the desirability of further testing. They stated that the VPFSC minimum peak allele levels were such (at 50) Rfus that the result was reliable. Minimum peak allele levels have recently been raised from 40 to 50 Rfus. I accept that scientific opinions may differ on the desirability of reproducibility. I do not consider that the failure to retest after the sixth test, taken alone or in combination with the other evidence relating to contamination demonstrates a significantly elevated risk of contamination sufficient to justify intervention by the Court.[11]

39 It was submitted that the specific error into which his Honour had fallen, and which would justify this Court in the giving of leave to appeal, lay in the test which had been formulated in [31].

40 Counsel noted first that his Honour had been asked to exclude the DNA evidence as a matter of discretion under s 135 of the Evidence Act 2008 (Vic), and as a matter of mandatory exclusion under s 137 of that Act.

41 Section 135 is in the following terms:

The court may refuse to admit evidence if its probative value is substantially outweighed by the danger that the evidence might -

(a) be unfairly prejudicial to a party; or

(b) be misleading or confusing; or

(c) cause or result in undue waste of time.

42 It was submitted that, at least in relation to criminal matters, s 135 largely replicates what has come to be known as the 'Christie discretion'.[12] It was accepted that, under that discretion, the onus rested upon the accused to justify the exclusion of evidence that would otherwise be relevant and admissible.

43 The first limb of the discretion, namely 'unfairly prejudicial', means prejudice which is unfair because there is a real risk that the evidence will be misused by the jury in some unfair way.[13] Both the second limb and the third limb, 'misleading or confusing' and 'cause or result in undue waste of time', potentially overlap with s 135(a). Both limbs have been invoked where there is a danger that the tribunal of fact will incorrectly assess the weight of the evidence, or will be confused as to its significance. Section 135 has also been invoked to exclude expert evidence which falls foul of the requirement that the admissibility of such evidence depends upon adequate disclosure of the factual basis for the opinion.[14]

44 Counsel for the accused also accepted that the requirement under s 135, that the probative value of the evidence be 'substantially outweighed' by the dangers then identified, meant that the onus that rested upon his client was a heavy one.

45 Turning then to s 137, it reads as follows:

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 accused.

46 This section mandates the exclusion of evidence if the Court concludes that the danger of unfair prejudice outweighs the probative value of the evidence.[15] Accordingly, s 137 is not a true discretion.[16] It was submitted that the balancing process required to be carried out operated quite differently to the exercise of the discretion under s 135. For example, the evidence in question would have to be excluded even if that balancing process came out only marginally in favour of the accused. Counsel for the accused submitted that, unlike s 135, s 137 did not cast any onus upon the defence. It was further submitted that, to the extent that his Honour had assumed that it did, his ruling in regard to the section was flawed, and should be set aside.

47 That error was said to be compounded by his Honour's failure correctly to apply s 142 of the Evidence Act 2008 (Vic). That section provides as follows:

(1) Except as otherwise provided by this Act, in any proceeding the court is to find that the facts necessary for deciding -

(a) a question whether evidence should be admitted or not admitted, whether in the exercise of a discretion or not; or

(b) any other question arising under this Act -

have been proved if it is satisfied that they have been proved on the balance of probabilities.

(2) In determining whether it is so satisfied, the matters that the court must take into account include -

(a) the importance of the evidence in the proceeding; and

(b) the gravity of the matters alleged in relation to the question.

48 Facts for consideration in relation to the admission of evidence can arise in a wide range of circumstances. For example, there may be issues surrounding the circumstances under which an admission was made, or which relate to an allegation of impropriety, or illegality, on the part of the police. The section provides that a trial judge, faced with having to find facts in order to determine admissibility, must be satisfied of those facts on the balance of probabilities, having regard to what at common law would be termed the 'Briginshaw principle'.[17]

49 Counsel for the accused submitted that s 142 imposed upon the Crown a legal onus of proof in relation to non-contamination, and that his Honour's approach in his ruling at [31] failed to reflect that burden. It will be recalled that his Honour said in that paragraph that 'the accused bears an onus in relation to the contamination issue'. He went on to observe, that it was sufficient (and, by implication from what he said, necessary) for the accused 'to prove that there [was] a real chance' of contamination either before or during the testing process.

50 Counsel next submitted that his Honour was wrong to hold that there had to be a 'real chance' of contamination, in order to trigger the potential operation of s 137, rather than a merely theoretical chance. It was submitted that the accused bore no onus of any kind to 'demonstrate' that the probative worth of the DNA evidence had been substantially eroded by any risk of contamination. Rather, it was for the Crown to establish, as part of its case, and as a precondition to the admissibility of the DNA evidence, that there was no such risk.

51 There are difficulties with each of these contentions. First, although the use of the word 'must' in s 137 mandates exclusion if the probative value is outweighed by the specified danger, the balancing exercise required of a judge in relation to that provision is analogous in key respects to that required under s 135. The judge must weigh, against each other, what have been described as 'essentially incommensurable considerations: probative value on the one hand and unfair prejudice on the other'.[18] In the words of Scalia J, this is like asking 'whether a particular line is longer than a particular rock is heavy'.[19] Clearly the balancing exercise undertaken by a judge under s 137 is no simple task. Any conclusion reached may well be one upon which reasonable minds can differ.

52 The submission by counsel for the accused that the onus rests throughout upon the Crown when s 137 is invoked is directly in conflict with the authorities. The New South Wales Court of Criminal Appeal has determined that, despite the fact that the section is couched in mandatory terms, and is not in that sense a discretion, the onus lies upon the accused to persuade the trial judge that the danger of unfair prejudice from the evidence outweighs its probative value. Of course, once that is established, there is no further latitude given, and the evidence must be excluded.

53 In Gilmour v EPA; Tableland Topdressing v EPA,[20] Santow JA, with whom Hidden and Adams JJ agreed, said:

As to whether the court should have excluded the evidence under the mandatory provisions of s137 of the Evidence Act, the short answer is this. Even if otherwise it were the case that its probative value in retrospect was outweighed by the danger of unfair prejudice to the defendant, the onus to have that evidence so excluded lay on the defence, who simply did not invoke s137 at trial. Clearly the onus to have such evidence excluded lies on the defence. Self-evidently this is because it is only the defence that can point to the danger of unfair prejudice, to be weighed against any probative value.[21]

54 The decision in Gilmour that the onus in relation to s 137 lies upon the accused is, as we have said, directly contrary to the submission put by counsel for the accused before us. We are, of course, obliged to follow a decision of an intermediate appellate court concerning the interpretation of legislation, such as the Evidence Act 2008 (Vic), which is uniform throughout much of Australia, and modelled upon Commonwealth and New South Wales legislation.[22] Once it is clear that the onus rests upon the accused, there is little scope for s 142 to assist this claim.

55 Secondly, as a matter of ordinary principle, his Honour's remarks in [31] must be read in context. Despite his use of the term 'prove', it is clear, when the ruling is read in its entirety, that he did not mean to suggest that the legal burden of proof lay upon the accused to establish either contamination, or the risk thereof, as a condition of the exercise of s 137. Rather, his Honour appeared to be speaking of nothing more than an evidential burden, which of course can be discharged by evidence falling far short of proof. Indeed, he appeared to have in mind only the weakest of evidential

burdens, namely one that rests upon an accused in what has been described as a 'tactical sense'.[23]

56 The rules as to evidential burdens exist for a number of reasons. One is the difficulty of proving a negative. For example, it is well-established that, on a charge of dangerous driving, the evidential burden rests upon an accused to point to some material which suggests that there may have been a mechanical defect, if he wishes to rely upon this defence.[24] Of course, an evidential burden can be discharged without the party upon whom it rests having to give evidence. The facts rendering the matter a live issue may be elicited through cross-examination.

57 It would be wrong, in our view, to require the Crown at the outset to rebut every possible fact which might be relied upon by the accused in order to avoid the exercise of an exclusionary discretion, or the power to exclude under s 137. Of course, if there is evidence, or some other material, to suggest that there is a realistic possibility of contamination, the legal onus rests upon the Crown to negate that possibility. That will ultimately be a matter for the jury. It will not ordinarily be a matter for a trial judge, who is called upon to make a decision only as to whether to permit the jury to hear the evidence. Plainly, a bare assertion from the bar table that there was a possibility of contamination will not, of itself, form any basis for the exercise of the power to exclude evidence under s 137.

58 Thirdly, counsel's submission must overcome a formidable obstacle. It is clear from his Honour's ruling, and from the more than 900 pages of transcript on the voir dire, that he did not regard the suggestion that there had been contamination as any more than the most speculative of assertions. His Honour made that plain when he said, at [43], neither the 'failure to retest after the sixth test, taken alone or in combination with the other evidence relating to contamination demonstrates a significantly elevated risk of contamination sufficient to justify intervention by the Court'.

59 That finding of fact was sufficient for the purposes of a ruling on the admissibility of the DNA evidence. No doubt, the possibility of contamination can, and will, be raised again at trial before the jury. So too will be the conflict between the opinions of Ms Federle and Mr Fowler, on the one hand, the experts to be called by the Crown, and that of Dr McDonald, on the other, the expert to be called by the accused. The weight to be accorded to these opinions is a matter entirely for the jury. It would not be appropriate, in general, for a trial judge, called upon to make an evidentiary ruling, to resolve a conflict between experts by preferring one opinion over the other. Still less should any such conflict be resolved by this Court in the imperfect circumstances, and necessary haste, associated with an interlocutory appeal.

60 It was for these reasons that leave to appeal was refused in both matters.

[1] [2010] VSCA 45 ('McDonald').

[4] If statutory warrant for having regard to merits on a leave application is required, it is to be found in s 297(1)(c) of the Act.

[5] [2010] VSCA 100.

[6] [2006] NSWCCA 112; (2006) 66 NSWLR 228.

[9] See, for example, Yates v Wilson [1989] HCA 68; (1989) 168 CLR 338.

[10] It was submitted below that this evidence was inadmissible because it was irrelevant. That argument was never tenable, and sensibly, was abandoned before this Court.

[12] R v Christie [1914] AC 545.

[13] Papakosmas v The Queen [1999] HCA 37; (1999) 196 CLR 297, 325 (McHugh J).

[14] Australian Securities and Investments Commission v Rich [2005] NSWSC 149; (2005) 190 FLR 242.

[15] R v Cook [2004] NSWCCA 52, [27].

[16] The heading to Part 3.11, 'Discretionary and mandatory exclusions', was inserted into the New South Wales and Commonwealth versions of the Evidence Act in 2007 and 2008 respectively, in substitution for the previous heading 'Discretions to exclude evidence'.

[17] Briginshaw v Briginshaw [1938] HCA 34; (1938) 60 CLR 336.

[18] R v Shamouil [2006] NSWCCA 112; (2006) 66 NSWLR 228, 238.

[19] Bendix Autolite Corporation v Midwesco Enterprises Inc [1988] USSC 122; 486 US 888 (1988), 897.

[20] Gilmour v EPA; Tableland Topdressing Pty Ltd v EPA [2002] NSWCCA 399 ('Gilmour').

[21] Ibid [46]. See also Polkinghorne [1999] NSWSC 704; (1999) 108 A Crim R 189, 197-8.

[22] Australia Securities Commission v Marlborough Gold Mines Ltd [1993] HCA 15; (1993) 177 CLR 485.

[23] Another term for such a burden is a 'provisional burden'. See the discussion by Lord Denning, 'Presumptions and Burdens', (1945) 61 Law Quarterly Review 380. See also R. Cross & C. Tapper, Cross on Evidence, (6th ed, 1985), 129-130.

[24] R v Spurge [1961] 2 QB 205.