ANNUAL DPP SOLICITORS’ CONFERENCE 2002
FORENSIC SCIENCE IN CRIMINAL LAW
Nicholas Cowdery QC, DPP
It is my pleasure once again to welcome you to the annual conference for solicitors in the Office. I hope that you have an enjoyable and productive day away from the routine work of your practices and exposed to some of the recent developments in the scientific world that touch on our work.
The theme of this year’s conference is “Forensic Science in Criminal Law” – a subject of which we will hear an increasing amount as time goes by and scientific advances have an even greater influence on the criminal justice process. The program for the day has an emphasis on DNA and drugs (although this afternoon you may deal with other forensic technologies). A couple of weeks ago in our Office training program there was an excellent session on forensic document examination with Paul Westwood. These are only some of the sciences that have a forensic application and which, therefore, we need to know something about.
Today we have several experts who have donated their time to explain to us recent developments in their fields and I thank them for their interest and assistance. I encourage you particularly to become involved in the panel discussions that are scheduled during the day.
I am going to use my time for a brief introduction to the subject of DNA. It is an extremely important development for us – the most significant advance of its kind since fingerprints, first used about 100 years ago.
DNA technology does have a significant role to play in the administration of criminal justice; but it must be acknowledged that, while it is an increasingly important tool in criminal investigation, it is not a “magic marker” conclusively identifying guilty persons. Its true contribution must be kept in perspective and there are still some issues to be addressed, as there are with any new developments of such impact.
Comparisons of DNA profiles are presently made within NSW (and within other jurisdictions) and you will hear more of that from our speakers. Australia is aiming to establish a national DNA database. Such a reference source hopefully will enable matches to be made more efficiently and from a larger pool than intrastate comparisons can use. There are some obstacles yet to be cleared to enable this facility to operate effectively through CrimTrac, the federal agency; and even when it is operating, legal requirements and the principles of proof will still need to be observed in all cases in which DNA evidence is used.
To a prosecutor, DNA evidence may mean the difference between an arguable case and a case against which there is no reasonably sustainable argument. To a defence lawyer, it may spell grim news – or it may mean complete exoneration for the client. Whichever side of a case the lawyer is on, the issues surrounding the sources and use of such evidence need to be understood.
The fictitious Horace Rumpole was an expert on bloodstains (following his sterling work for the defence in the Penge Bungalow Murders case, of course). He was able to draw upon a long record of the use of biological material in criminal investigations. Indeed, there are records of bloodstains being used for forensic purposes as early as 384 AD. Only since about 1985 have we been able to benefit from DNA profiling.
James Watson and Francis Crick modelled the structure of DNA in 1953 and were awarded the Nobel Prize in 1962.
Deoxyribonucleic acid (DNA) has been described as the blueprint for life. It is the fundamental natural material that determines the genetic characteristics of all life forms and the DNA molecule is made up of two strands of alternating units of a sugar, phosphate and bases, twisted into a spiral. It codes for the make-up of the animal or plant in which it is contained, the code being in the bases where the links occur between the two strands of DNA. There are four different kinds of bases and the proportions of each of the bases and the order in which they are arranged code for each species of living thing. (A section of DNA, containing a particular sequence of bases, may be described as a gene. Chromosomes are larger groups of genes, nearly 100,000 in each case.) The sequence of the bases along the strands of DNA is code that we can read and sections of the strands can be replicated for examination.
For humans, DNA is found in all cells in the body which contain a nucleus – red blood cells are excluded. There is nuclear DNA, inherited from the father and the mother in random combinations and only identical twins have the same nuclear DNA. There is also mitochondrial DNA, in the mitochondria of nucleated cells, which is a copy of the mother’s DNA. It is more expensive to analyse and the results may not be as conclusive. (The first conviction on the basis of mitochondrial DNA was not until 1996, when in the USA Paul Ware was convicted of the rape and murder of a young girl after the testing of a hair found on the girl). The DNA in one individual is identical in every cell. It has been estimated that over 99% of the DNA in one human is identical with that of every other human, so the remaining less than 1% gives us the individual differences that may be detected.
Between the sections of DNA (the genes) which operate for specific functions (eg genetic information about race, hair colour, eye colour, height or predisposition to disease) there is so-called “junk” DNA, base sequences that are of no identifiable functional use. This “junk” DNA was identified in 1980 and was found to be extremely variable between individuals. DNA analysis uses this “junk” DNA, which consists of sections of repeating short sequences, for comparison purposes. Usually (at least in the Profiler Plus system that is used in Australia) 9 sites (or loci) are selected plus the sex indicator.
The statistics of these comparisons and the probability calculations derived from them are the part of all this that is ultimately of significance to the forensic work done by lawyers in the identification of individuals. We talk of “match probability”, meaning the probability that a randomly selected, unknown, unrelated person would have the same DNA profile as the suspect. (The way in which those calculations are done and the factors that bear upon them I leave to others.)
We are not very protective of our DNA – we carelessly leave it everywhere. That is why it is so useful for lawyers. It is in our blood (the white cells only), semen, mucous secretions, hair roots, skin, faeces, urine, vomit, bone marrow and in cells in saliva, sweat and tears. We leave sweat and skin cells all over the place – on just about everything we touch and wear next to our skin, including other people’s hands when we shake them, car steering wheels, doorknobs, knife handles and guns. We leave saliva on masks, balaclavas, postage stamps, envelopes, chewing gum, the rims of drinking glasses and cigarette butts. Offenders may leave DNA on or in victims – and, importantly, the victims may pass their DNA to the offenders or the offenders’ clothing or possessions. (Last month a man was convicted of a sexual assault in the USA where the victim’s dog’s hairs were found on his trousers – it was a Shih Tzu named Casper.)
If we bleed, spit, ejaculate or otherwise make a cellular deposit onto something, we leave our signature – and a signature that cannot be forged. We leave a DNA trail wherever we go – and it is our trail, not just a trail like somebody else’s (unless we have an identical twin) – and lawyers (especially criminal lawyers) love to follow trails. Nevertheless, the ultimate question remains an appreciation of where the trail has led us – because that very carelessness about protecting our DNA may enable it to be found on things and at places with which we have only an innocent connection.
All trails are not equally clear. Our experience here shows that blood has a 90% chance of producing a DNA profile; saliva on a cigarette butt 67% but on a balaclava only 43%; sweat on the handle of a weapon 17%; fallen hair (with dead roots) 25% but plucked hair much higher.
Although we are so careless about losing our DNA, we are usually much more careful about giving it away. It is a part of us – it is private – it is something that we should not ordinarily be forced to part with. But many of us are. It is exceptionally easy to give away, too – even less of a process than giving fingerprints. A cotton swab rolled around the inside of the cheek is all that is required and is the most common (but not the only) means adopted in Australia.
The first use of DNA evidence in criminal investigation was in England in 1985/6 and it produced some interesting consequences. Two women had been raped and killed and the police believed that one person was responsible for both homicides. A suspect confessed to one, but denied the other. Professor Alec Jeffreys of Leicester University, who had been researching DNA and had discovered in 1984 a method of identifying individuals from DNA, tested some crime scene samples which showed that the killings were in fact likely to have been committed by the same person. He tested the suspect who had confessed – but there was no match. There was a mass screening of nearby villagers (as we have had in Wee Waa in NSW in the investigation of a rape) and the offender was discovered after it became known a few years later that he had persuaded a friend to substitute his blood. Colin Pitchfork was ultimately sentenced to two life terms.
Around 150 mass screenings have been conducted in the UK, I understand, in respect of homicides and rapes. There have been over 75 matches from those exercises including, as at mid-2001, 20 matches for murders and 33 for sex offences. Those matches have enabled some suspects to be excluded and investigations to continue along more productive paths.
In the 5 year period from mid-1995 to mid-2000 in the UK the database received 817,448 profiles from suspects. In that period there were 77,522 matches of person to crime scene and 11,073 matches of crime scene to crime scene. The UK database produces a cold hit rate of 18%, which compares favourably with a 10% rate for fingerprints.
In NSW we have conducted three mass screenings – in Wee Waa, in King’s Cross and on the north coast. In the Wee Waa rape case in 2000 about 600 male inhabitants of the town between certain ages volunteered, on request, to provide samples for DNA testing. (Twelve eligible men, including a solicitor, refused to participate.) The offender confessed as he gave his sample (which, on later analysis, did provide a match with the crime scene). However, it should also be noted that DNA profiling of several suspects had already been undertaken at an earlier stage of the investigation and they had been excluded (with consequential benefits for them and for the course of the investigation).
The first person to be convicted of a crime – rape – directly on the basis of DNA evidence was Robert Melias, also in the UK, in 1987.
The first person to have a conviction overturned on the basis of DNA evidence was Gary Dotson in the USA in 1989. He had served 8 years of a sentence of 25-50 years for rape.
The first Australian case using DNA evidence was in 1989 in Canberra. There were charges of sexual assault of a woman against one Desmond Applebee, who at first said that he wasn’t there at all. DNA profiling from blood and semen on the victim’s clothes showed that there was one chance in 165 million that it was not his. After a period of attacking the police investigation, he changed his defence to one of consent by the woman. The jury having heard evidence at first of his rather shaky alibi, then his attack on the police investigation, then having heard that, well, he was actually there but she consented, had little difficulty ultimately in convicting him.
A few months later in 1989 in Melbourne a serial rapist, George Kaufman, pleaded guilty to a number of offences after DNA matching established that he was probably the perpetrator. His DNA was initially identified from samples given by his wife and daughter – later he provided a blood sample himself and ultimately he confessed.
The use of DNA evidence in criminal cases has now become a daily phenomenon in a great many countries the world over.
From the prosecutor’s perspective, DNA evidence plays at least the following three roles in the criminal justice process.
a) Matches of DNA may enable inferences to be drawn about the involvement of individuals in the commission of offences. DNA may be found at crime scenes; it may be obtained from suspects; profiles may be obtained from a database. Comparisons, one to another, may enable inferences to be drawn about the number of offenders involved and the possible identity of those offenders. Those inferences may point powerfully to the guilt of a person accused by establishing that he or she had a personal connection with a relevant place or thing or other person.
b) Those same comparisons may also indicate, in this case with certainty, that an individual was not involved in a particular crime. That important consequence can lead and has led to individuals being excluded from investigations. There are obvious resulting benefits to the individuals concerned and also to the investigation process itself, specific individuals no longer being subjects of interest. People with criminal records may not be investigated if they can be excluded at the beginning. Alibi evidence may not need to be obtained and investigated. The “usual suspects” (of Casablanca fame) need not be rounded up as often. This may apply to hundreds of suspects a year in jurisdiction the size of NSW.
c) For similar reasons, initiatives such as the NSW Innocence Panel (and Innocence Projects in other jurisdictions, often run by law teachers and students) can assist wrongly convicted persons to demonstrate that they could not have been involved in the offences for which they were convicted. Many have been released from prison in the USA and even from death row.
These are the results that can be achieved from samples on items found at crime scenes. Issues of concern to many – and of interest to lawyers especially – are: with what should those crime scene results be compared? And: what conclusion should be drawn from any such comparison? Legislation now addresses these questions.
In NSW the Crimes (Forensic Procedures) Act was passed in 2000 and came into operation on 1 January 2001. It substantially follows the MCCOC Model Bill, but puts buccal swabs in their own, third category (although the rules that apply to them are virtually the same as those for intimate samples).
All jurisdictions in Australia have now enacted legislation which falls loosely into three categories:
a) those closely following the Model Bill (NSW, the Commonwealth and the ACT);
b) those that follow it in some respects (Tasmania, Victoria and South Australia); and
c) those that do not follow it at all (Queensland, the Northern Territory and Western Australia).
These differences create inconsistencies in the description of the offences for which samples may be taken, the definitions of intimate and non-intimate samples, the nature of samples able to be taken, the power of police to take samples, the rules for matching samples and the retention or destruction of samples and records. These inconsistencies have the potential to cause evidentiary problems if and when the CrimTrac DNA database is under way and samples are matched across State and Territory borders.
Nevertheless, there remain some concerns among defence lawyers in particular about the use of this technology (and it is probably healthy for the introduction of any new tools – especially those based on science – to be greeted cautiously and even with slight over-reaction to the potential downside). Some of those concerns are as follows.
· It is a dangerous simplification to say, as many people do, that because a DNA match has been made, the offender has been identified and conviction will follow automatically. DNA provides a link between a person and a place or thing or another person – how that link occurred and the significance of that link in the overall case remain to be proved.
· A match produces only a statistical probability of a link and that must be borne in mind – it is not an incontrovertible result.
· Screening of significant parts of the population and mass screenings may do nothing more than to provide, at great financial and human rights cost, more links of more people with more scenes. Again, such links remain to be explained.
· As a matter of principle, in a free society, personal information should not be taken compulsorily from citizens and stored against the possibility of future wrongdoing. There should first be evidence justifying such action.
· There are implications in the procedures we are following for the presumption of innocence and the freedom from forced self-incrimination.
· The right to privacy is at risk. Genetic information is being provided, sometimes under compulsion, and even if there is no present risk there is the possibility of “function creep” in the future, with the information being adapted to other purposes. This is particularly the case in those places where the sample and not just the DNA profile may be retained. Information gathered, especially by compulsion, may be abused by the unscrupulous (eg apparently governments in Iceland and Tonga have sold genetic information about their citizens to researchers without the consent of the subjects). Insurance companies may have a great interest in genetic information – but quaere whether they would be interested in profiles from “junk” DNA? (These concerns could probably be overcome by appropriately foresighted legislation.)
· Some are concerned that senior police officers can make orders for the taking of samples in certain circumstances and that the protection of the intervention of an independent judicial officer is denied.
· Prisoners should not be tested just because they are prisoners and might have committed other offences or might re-offend in future. They should be tested only if there are grounds for such suspicions presently existing. (For example, most murderers do not re-offend and many of them have not offended in the past, but they are top of the list of prisoners to be tested.)
· There should be tighter controls on the admissibility of this evidence to ensure that prescribed procedures have been followed in all cases in which it is used. That is, discretionary admission where a formality has not been observed should be removed.
· False matches will occur from time to time, especially with comparisons with large databases. There have already been false matches in the UK and in New Zealand (in the former case from the use of only a small number of loci and in the latter case probably resulting from laboratory contamination). It is particularly discriminatory against prisoners for them to be at the greatest risk of false matches, because they are the most likely members of society to be prejudiced by such results and to be unable to defend themselves successfully.
· Reliance on DNA may divert resources and efforts from more traditional and effective forms of policing.
· There is a risk of DNA material being planted at crime scenes (or other forms of tampering along the line of testing) or having been deposited there innocently, so room must be left for explanations to be made.
· There is a risk of faulty laboratory results or contamination from faulty procedures. Even something as simple as mis-labelling may lead to false conclusions. Results of testing may be misinterpreted.
· A potential volunteer who refuses to comply with a request for a sample can easily become a suspect.
· Different rules in different jurisdictions may enable investigators to have access to evidence that they would not be able to rely on in their own jurisdiction.
There are grounds for much confidence and optimism about the benefits to crime fighting able to be provided by DNA profiling. Nevertheless, we should remain alert to possible dangers and to the protection of fundamental human rights. The end will not always justify the means, even in the protection of society from crime.
If the science is pursued with competence and integrity, however, it will provide another basis for the happy marriage of science and the law in the forensic environment.
The other speakers today will take you through the details of the science, the
legislation, practice and experience in the application of this technology. I wish you an interesting day.