Tuesday, March 23, 2010

Possession and internet files

The meaning of possession of electronic files has been established by the Supreme Court of Canada in R v Morelli [2010] SCC 8. This case concerned allegedly pornographic internet files. Central to the requirements for possession is the concept of control.

The Court split 4-3. The minority made much more use of case law than did the majority, and the majority relied more on fundamental principles. The majority held that knowledge is a requirement for control, and that control is not constituted by the mere viewing of an internet file. Control requires knowingly acquiring the underlying data file and storing it in a place within one's control. The mere automatic caching of an internet file does not of itself amount to storing it unless that caching occurred with knowledge that the file was retained.

The minority regarded control as existing when the accused willingly took or maintained the use or benefit of the material, so that it did not need to be on his computer's hard drive.

In this case a search warrant had been obtained without sufficient grounds (as held by the majority) and the evidence had been obtained improperly. Applying R v Grant [2009] SCC 32 the majority held the evidence to be inadmissible.

Evidence of fingerprint matches

For an interesting article on how fingerprint evidence should be given, see New Scientist, 22 March 2010 , "Fingerprint evidence to harden up at last" by Linda Geddes.

Thursday, March 18, 2010

The Waihopai spy base case

In this site, which is aimed at the decisions of leading appellate courts, I do not usually comment on trials. However, today our little nation is abuzz with discussion of the implications of what the media call the Waihopai spy base case.

Some people damaged some big plastic domes that cover secret communications facilities. I am vague on this description, but for me the most interesting thing about this case is the revelation that the big white domes can be slashed with a knife to expose the underlying things. Aerials and whatnot. The people were put on trial and yesterday were acquitted by a jury of offences like burglary and wilful damage.

What was their defence? That is not really the point. What matters is that a jury decided the case, and acquitted when a judge almost certainly would have convicted.

The case illustrates the role of juries in bringing community standards to the law. The common law's origin is the customs of the realm, and those customs were based on what people thought was reasonable. If the community thought that what a person believed and what he did were reasonable, then he would not be held to be acting illegally. You can apply the same criteria today to the criminal law. Although offences are now statutory, their definitions will always - except for some minor offences of absolute liability - be such as to permit acquittal of people who have held reasonable beliefs and who have acted reasonably in pursuit of those beliefs. Sometimes the law is more generous, allowing a defence if the belief was unreasonably held as long as it was honestly held (for example, self defence).

The best arbiter of what a community believes to be reasonable is a jury. This is recognised by courts (see the discussion by Heydon J in AK v Western Australia [2008] HCA 8 at paras 90-98) and by law reform bodies (see the New Zealand Law Commission report "Juries in Criminal Trials" para 78). There are limits to the extent to which juries should be admired (as I have suggested). Even so, if you say the jury was wrong in this case, you have to show that community values are such that what the defendants did was, in the context of what they reasonably believed, unreasonable.

We disagree, but we won’t say why

The majority in Morgan v R [2010] NZSC 23 (16 March 2010) do not explain why they reach the opposite conclusion to that of the dissenting Chief Justice. All Justices agreed that the issue came down to whether there was unfairness in admitting the contested evidence. The Chief Justice explained in detail why she thought there was unfairness. In the absence of a detailed response by the majority we are left feeling some disquiet about the soundness of the majority's conclusion.

Here the contested evidence was a statement previously made by a witness who was now hostile to the extent that he claimed not to remember the events in issue, and the making of any previous statement about them.

In contrast to the earlier position, under the Evidence Act 2006[NZ], any statement that is admissible is admissible to prove the truth of what it asserts. Where a witness is declared hostile, a relevant previous statement by that witness can become admissible. It may be elicited in cross-examination by the party that called the witness: s 94, or the Judge may permit such cross-examination even if the witness is not hostile: s 89. If the witness is hostile to the extent of refusing to be cross-examined, it is arguable that he is not a "witness" within the definition of that term, and his prior statement is hearsay. But even if it is not hearsay, fairness should require reasonable assurance that the statement is reliable when the s 8 discretion to exclude it is being considered.

The matter comes down to this (as expressed in the majority judgment):

"[41] Parliament has legislated to make previous statements of a hostile witness admissible as proof of their contents without adoption, presumably on the basis that the witness will be subject to cross-examination. The reality of that premise may differ from case to case. Parliament's policy decision should not be undermined by too ready a resort to s 8. It certainly should not be undermined on any generic basis. The ultimate question will always be whether the evidence is unfairly prejudicial in all the particular circumstances of the case, of which opportunity for realistic cross-examination will always be important."

The majority considered that in this case the witness had implicitly adopted his previous statement when he was cross-examined by the prosecutor. But this was on the basis of the last two questions in the critical passage, whereas the Chief Justice put these in a larger context and concluded that the witness had consistently refused to acknowledge the previous statement. Because she gave more detailed reasons, she is more convincing on this point.

The majority held that difficulties that might have arisen if defence counsel had attempted to cross-examine the witness on the prior statement were not such as to give rise to unfairness. No elaboration of that was offered. So we don't know why it was fair to admit the statement. The Chief Justice explained her conclusion by pointing out that in this case there was no other evidence sufficient to provide a reasonable assurance that the prior statement was reliable. The majority alluded to "a number of circumstantial features pointing to Mr Morgan's involvement, established elsewhere in the Crown's evidence" (para 45).

Still, the case is authority for, or illustrates, the following points: statements are admissible for their truth; admissibility is subject to s 8; there is a need for particular care to avoid unfairness when there can be no cross-examination of a hostile witness; the judge should hear evidence in voir dire before ruling on admissibility and should include an exploration of the witness's willingness to be cross-examined.

A significant omission from the factual narrative is whether the witness, a cell-mate of the accused, knew what the accused was charged with at the time he reported to the police that the accused had confessed. The Court of Appeal judgment summarises the facts ([2008] NZCA 537):

"[27] Mr Roskam shared a cell with the appellant shortly after the appellant was remanded in custody. Mr Roskam said in a statement to the police that he and the appellant had been watching a programme called “Police 10-7” which featured the robbery at issue in the present case. The appellant became very excited, and subsequently (some days later) told Mr Roskam that he had committed the robbery."

In the absence of this important fact, I will assume that the cell-mate knew, at the time he reported the confession, what the accused was charged with.

On that basis, the majority judgment contains a logical fallacy. It is fundamental but easily overlooked:

“[45]  One of the matters that will have significance in the s 8 assessment is the view that the Judge forms of the inherent reliability or otherwise of the statement in issue.  In this case Mr Roskam’s statement that Mr Morgan had confessed to him, in an apparently spontaneous manner, his involvement in the robbery was substantially supported by a number of circumstantial features pointing to Mr Morgan’s involvement, established elsewhere in the Crown’s evidence.”

This was not a case where the alleged confession contained details that only the offender could have known. It amounted simply to the accused, watching a news item about the robbery on television in a cell with Mr Roskam, allegedly yelling out “yeah, yeah!”, getting excited, and saying it was him (see para 8, the passage from the prosecutor’s cross-examination of Mr Roskam). Therefore, the “number of circumstantial features” that the majority say supported the reliability of the statement in issue (that is, Mr Roskam’s statement that the accused confessed) were not in the alleged confession but were indicative of the accused’s guilt. But here the majority confuse proof that the alleged confession had been made with proof that the alleged confession was true. The latter is not a substitute for the former. Just because a person may be guilty does not mean he is likely to have confessed.

The question is, "does this evidence, the confession, exist?" The majority say that if the confession existed it would fit with other evidence against the accused, therefore the confession existed. You can see the circularity. If the confession did exist, then the other evidence would indeed be useful in assessing whether it was true; but we have not got to that stage yet. To decide whether the confession existed, we would have to assess the credibility of the witness and that would include examining his honesty and whether there was any incentive for him to lie. He was endeavoring to retract his evidence, and that would be a relevant factor too. If the evidence of the existence of the confession was of sufficient value to have a tendency to prove that the confession existed, then it would be relevant evidence. Then its probative value would have to be assessed, and weighed against its unfairly prejudicial effect. The probative value could be assessed in Bayesean terms as a likelihood ratio: the probability of the witness saying that the confession existed, on the assumption that the accused was guilty, divided by the probability of him saying it existed, given that the accused was not guilty. If the witness had low credibility, he might have been almost equally likely to say that the confession existed, whether or not the accused was guilty. The likelihood ratio, or the probative value of his claim that the confession existed, would be very small. The risk of unfair prejudice would outweigh the probative value, because the jury would be likely to attach too much weight to the witness's claim that the confession existed.

After conscientiously advising care in the application of s 8, the majority misapply it to the probative value of the confession instead of to whether the confession existed. It is difficult to accept that a judgment flawed in this way can enhance the standing of the Court.

Of course, if Mr Roskam did not know what the accused was charged with, the other evidence of guilt would support his credibility. If that fact had existed, however, it would have been highlighted in the judgments. 

People interested in the real politik of law will note the distancing between the Chief Justice and Wilson J, and the apparent collegiality between Wilson J and the other judges whose judgment he delivered (Blanchard, Tipping and McGrath JJ). Ho hum. And flash forward! "I think, but dare not speak."

Wednesday, March 03, 2010

Small, but perfectly formed – judicial acceptance of LCN DNA analysis

Updating the forensic use of LCN DNA analysis: R v Wallace [2010] NZCA 46 surveys developments and refers to R v Reed & Garmson (2009) EWCA Crim 2698. Brief mention of Bayes' Theorem, led the Court in Wallace to the following "insight" (para 87):

"As a matter of logic, what all this means for criminal trials is that with low level DNA profiling it is not so much a question of the particular technique or method. This can, if rather painfully, be explained to judges and jurors. It is the philosophy of the approach that is important: the uncertainty of the method of transfer does not diminish the fact of the matching DNA profile for the former does not invalidate the latter. The method of transfer however is of great moment for the court, whilst it does not necessarily concern the scientist."

That is to say, a match is a match is a match, but the court needs to know why there is a match.

The Reed & Garmson dicta were summarised in Wallace (para 97):

"Three points can be made about this decision. First, it is apparent that the Court of Appeal of England and Wales accepted that at least under defined conditions Low Template DNA can form admissible profiles, capable of reliable interpretation. Indeed, during the course of the Reed & Garmson appeals both appellants abandoned their general attack on the reliability of Low Template evidence using the LCN process. Second, the Court of Appeal of England and Wales prescribed what might be called a "safety" floor limit. Above the range described by that Court as being a stochastic threshold of 100 and 200 picograms results can be so produced which are capable of reliable interpretation. Third, in the view of that Court a challenge to the validity of the method of analysing DNA by the LCN process should no longer be permitted where the threshold limit is exceeded." [the Court's emphases]

There may be some circumstances in which whether there is a match can be an issue, but these are limited (on current understanding) to cases where the amount of DNA from the crime scene was so small – around 100 to 200 picograms (1 picogram = a millionth of a millionth of a gram) that random errors (called stochastic effects) could cast doubt on whether a match existed (applying Reed & Garmson).

In Wallace it was argued for the appellant that it was incorrect to regard the relevant sample of DNA from the scene as coming from a mixed source, and therefore it was wrong to conclude that it did not exclude the accused. This was an issue of interpretation and the evidence supporting the appellant's view was not in this case sufficient to cast doubt on the correctness of the verdict. The Court emphasised that DNA evidence must always be evaluated in the context of the other evidence in the case. In Wallace the DNA evidence which was the focus of this appeal was not significant in that context.

I should add that I have summarised the facts in Wallace a little inaccurately in the interests of simplicity. The DNA just referred to was actually alleged to have been from the victim, and was found on a metal bar, allegedly the murder weapon, which the prosecution claimed to link to the accused.

Another sample of DNA was from the victim’s shoelace, and was allegedly from the accused. However this latter DNA was (para 33, 38) thirteen times more likely to have come from the accused or a paternal relative as from any randomly chosen New Zealand male. The trial court, as emphasised by the Court of Appeal, made it clear to the jury that this evidence did not prove the identity of the accused as the murderer, but it was merely consistent with the prosecution case. In reality – and contrary to the prosecution’s disavowal at trial - this DNA evidence was highly probative of guilt.

To say that the DNA was thirteen times more likely to have come from the accused (or a paternal relative) than from a randomly selected male means that if the likelihood of a random match is x, the likelihood of a match with the accused or such relative is 13x. The Bayes likelihood ratio is 13. Despite the protestations to the contrary at trial, this evidence was highly probative of guilt.

The appellate court needed to be satisfied that the other evidence in the case proved beyond reasonable doubt that the accused was the murderer. This is because, in Baysean terms, if the prior probability of guilt was only 0.90 (let’s assume this is not proof beyond reasonable doubt), the DNA on the victim’s shoelace would have increased that to a probability of guilt of 0.99. That is, this DNA evidence would have removed a reasonable doubt if the other evidence only proved guilt to a probability of 0.90. It would have been highly probative and important to the prosecution case, and errors in its interpretation would have been significant.