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Australian Law Reform Commission - Reform Journal |
MAKING FORENSIC SCIENCE WORK
some ideas for reform
- Separation of powers
- Admissibility and weight
- Conclusion
- How can non-technical courts make sense of scientific evidence given the enormous increases in complexity over the last half-century? The notable role played by forensic science in some recent miscarriages of justice has left many people feeling cynical about the legal system's ability to comprehend this sort of evidence. Eric Magnusson believes that it is time to reassess the fundamentals.
Associate Professor Eric Magnusson teaches chemistry and carries out research on the electronic structure of molecules at the University College, Australian Defence Force Academy. He claims expert status in the comprehension and assessment of science in courts on the basis of several decades helping students comprehend science and then assessing the result.
Forensic scientists in Australia are watched more carefully and the profession has been made more accountable than ever before, but it is still agonisingly difficult to judge the quality of forensic science's contribution to justice. Apart from strong reactions to sensational cases in which science played a major role, it is hardly ever evaluated, certainly not in any systematic way.
Since nobody examines the profession as a whole the writer thought it would be interesting to examine the individuals and conducted a shoddy sort of survey in the months before last year's National Forensic Science Summit. Forensic scientists in four states were prodded for their views about science in the Australian legal process.
The results were rather alarming. Alongside the ethics, professionalism, detachment, and skill was a large dose of cynicism. Few thought that science was serving the community up to its potential and none thought that courts were using scientific evidence scientifically. None had any confidence that a court would find the truth if they unexpectedly found themselves facing incriminating scientific evidence, charged with a crime they did not commit.
So, at least one group of knowledgeable people believe that science in courtrooms needs some reform. Only the best science should be used for investigating crime and the courts, when they hear scientific results, ought to assess them scientifically. Mistakes can never be completely eliminated, so if not all science is good, courts must be enabled to tell the difference between the good and bad varieties. This agenda for reform is easy to state. How hard will it be to produce it?
A quick answer to the reform question would acknowledge the salutary improvements in the quality of the laboratory science and its courtroom presentation over the last 20 years. Robust systems have been introduced to assure the community that most of the laboratory science is of high quality, and that the practitioners are ready for change about as quickly as the changes in science and technology demand.
The picture is patchy but the gaps are filling in, not least because the National Institute of Forensic Science is working hard to establish training courses where none existed and encouraging the state systems to extend the cover of accreditation over what is a very wide and uneven range of forensic science disciplines.
In Australia, as in other democracies with similar justice systems, science can still fail in the courtroom. However, human failure is now much more likely to be the cause than a scientific failure in the laboratory. Automated equipment and better methodologies solve some human problems but others are less easy to mechanise. Scientists worry most about the way the evidence will be dealt with in court, but there is potential for failure at every stage.
Separation of powers
Some errors result from the way the evidence was handled while still on its way to the laboratory. Others derive from an inadequate attention to the 'separation of powers'. The rule for investigators must be different from the rule for experts. The former must look for evidence that will incriminate but scientists must test the evidence hard to see if it might exonerate. They should only claim value for a report if all alternative explanations have been rigorously excluded.Science loses its special value if it is owned by only one side. The aim must be to install proper, even-handed practices in all the sub-disciplines and, as well, control the pre-laboratory part of the process. Verbals and alibis needed special rules, maybe crime scenes do too.
Science is science whatever its use in the community and, of all the uses, the service of justice should surely entitle a scientist to the full support of the scientific professions. Sadly the professions have never offered their help to the courts in the difficult job of assessing an increasingly complex science. And the courts have never let slip the suggestion that they need any. Now, maybe, it is time for courts to receive help from the independent scientific authorities, apply the standards of accuracy developed by the professions and forego the old idea of hearing only what happens to be presented to the court.
Admissibility and weight
The assessment of science falls naturally into two processes. The second, deciding the weight of the evidence, ought not to be considered until the first, admissibility, has been examined. Admissibility questions mix with the evaluation questions about as well as oil mixes with water.Admissibility calls for a yes-or-no answer - is the science well enough done to be safe for the jury to hear? If not it should not be admitted. Of course, but the primary question is 'How could a non-technical court know what's safe and what's not?', to which the answer is 'don't let science into the court without the information needed to give it a proper scientific assessment'. If it isn't scientifically assessable, it should not be admissible.
If judges in pre-trial hearings were provided with the criteria that scientists would use they could easily become competent in ruling scientific evidence admissible or inadmissible. The jury can then decide its weight. Otherwise, the jury has to do two incommensurable tasks together: determine the validity of the science to count as evidence and estimate the reliability of the evidence to be used to convict. The second, not the first, is where their real competence lies.
The two tasks can easily contaminate each other. The danger is especially severe when the strength of a strong item of evidence leads a jury to disregard the sloppiness with which it was gained. Similarly, the weakness of weak evidence could easily be ignored if the highly competent manner in which it was obtained attracts too much attention.
The possibility of contamination has to be considered because science is complex and juries can be easily confused. Even if they postpone asking for professional assistance in assessing science now, courts eventually will be forced to seek it by exploding technology. The jury can then return to the job they were called to do.
Science is a very broad collection of disciplines. Although some believe that scientific evidence is 'just like any other kind of evidence', its potential to change the law (it was science that made us change the law about potential incriminatory tissue samples) to strengthen the law (when it is really objective) and to frustrate the law contradicts that. Scientific evidence calls for a new, more sophisticated, approach in the courtroom.
For example, there are four different ways to test scientific evidence in the courtroom because the arguments fall naturally into four different categories. They stem from fundamentally different kinds of scientific investigation and each cries out for its own proper treatment.
Observe how differently we need to treat evidence from these two categories to be sure about safety:
Again, note how fundamentally different are results from these two categories:
- the result obtained from an instrument used for a single precise measurement (like the amount of heroin in a victim possibly murdered)
- the result you get when a scientist forms an opinion from many observations, no one of which could sustain it (like a pathologist's conclusion about the time and cause of death).
The differences in the arguments are real logical differences. Unless they are handled differently, courts will fail to apply the scientific safeguards or miss seeing the signs of quality needed to determine first admissibility and then weight of scientific evidence in a systematic and professionally appropriate way.
- the result of a qualitative test (like a conclusion identifying cannabis in a resin sample)
- the result of comparisons of characteristics, including those of the whole community (like a report that two tissue samples match in characteristics said to be very rare in the community, one sample having come from the body of a rape victim and one from a suspect).
Conclusion
Used professionally, science is ready to offer much more to the justice system than it can now. The participants in the process will be acting within their competence. The merits of the evidence will start to count more than the merits of its presentation. The risks of misunderstood science will be minimised. Control of the court process will pass back to the court.The justice system will be able to take advantage of improvements in the practice of forensic science and simultaneously be less vulnerable to the possibility of bad science being used in prosecutions. Finally, the justice system will become less vulnerable to people who mislead or confuse the court by capitalising on the complexities which forensic science unavoidably carries with it.
The National Institute of Forensic Science, R&D Park Centre, 2 Research Avenue, Bundoora Vic 3083, telephone (03)9459 4299.
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URL: http://www.austlii.edu.au/au/journals/ALRCRefJl/1996/3.html