CLIFF FALL IN SYDNEY
By Rod Cross, Physics Department, Sydney University.
Updated 1st March 2012
In November 2008, Caroline Byrne�s boyfriend was found guilty of throwing her off a cliff at The Gap in Watson�s Bay. Some of the forensic evidence presented at his trial can be found in the Journal of Forensic Sciences (2006) article .
Less than 10% of the information I presented to the police was presented at the trial, presumably because of the technical nature of much of that evidence and because of the limited time available for the trial. The defence were given access not only to all of that information but also to handwritten notes, 278 email messages to and from the police and to all video film of experiments undertaken over the five year period from 2003 to 2008. It is not certain whether they understood it, judging from the following exchange at the trial:
TERACCINI: 5.8 metres is just that, isn�t it
Professor? If the rate is 5.8 metres, that�s what it is, isn�t it?
A: No.
Q: No?
A: No. Yes, no.
Q: You agree, don�t you?
A: No. I don�t agree with what you are
saying.
Q: If you have a person running 5.8 metres.
A: Per second, you mean?
Q: Yes. That�s the rate they run, isn�t it?
A: No, that�s the speed at which they run.
Q: I�m sorry, speed they run, correct?
A: No, that�s the average speed over the
whole 50 metres of their race.
Q: Yes. If we break it down, it�s 5.8 metres
per second. Correct?
HIS HONOUR: I don�t understand the question.
Can you break down an average speed?
Q: If you jumped in an elevated fashion, do
you agree that you could rotate and land on your head?
HIS HONOUR: The answer is Yes, if you impart
torque at the point of departure and No if you don�t.
TERACCINI: Thank you, your Honour. Is there no
way of knowing whether you will rotate or you won�t when you jump off with the
elevated broad jump?
TEDESCHI: I object. I don�t understand the
question.
TERACCINI: Do you agree that there�s no way
of knowing whether you would rotate or not?
TEDESCHI: I object to the question. It�s a
meaningless question.
HIS HONOUR: It�s a meaningless question.
Move on, Mr Terracini.
Q: Does it make any difference to how
long it takes to fall if a person is flailing arms, flapping legs, things of
that kind?
A: No.
Q: What about the angle or the part of the
body that first comes into contact with the hard object at the bottom?
A: What about it?
Q: Do you hold yourself out to be an expert
in gait analysis?
A: I have written one paper on that subject,
so that makes me an expert on that particular part of the subject.
Q: And what particular part of gait analysis
have you published?
A: The paper of mine that you previously
quoted on walking, running and jumping on a force plate.
Q: And the force plate is used for what
purpose?
A: The measurement of the force on the
ground.
Q: Does it have anything to do with falling?
It doesn�t, does it?
A: No. There is no force on the ground when
you are falling through the air.
And so on. At the committal hearing, Terracini made the comment that
human motion cannot be studied using physics since the human body is much too
complicated. As an example, he said
�Not everybody can hit a golf ball like a champion. It�s self-evident. It�s
got nothing to do with physics. Nothing. It�s got to do with your ability.�
In fact,
the swing of a golf club can be
accurately modelled as a double pendulum. If the laws of physics had nothing to do with swinging
a golf club, then golfers could
presumably hit a golf ball
just as far with a 20 gram club as
with a 400 gram club. In fact, they wouldn�t have to hit the ball at all. They
could simply use will power or
spiritual guidance.
My
conclusion from all of this is not that barristers should learn elementary
physics but that the jury system is fundamentally flawed when it comes to the
examination of expert evidence. The evidence should be carefully examined in
the first instance by other experts, not by barristers, not by the police and
not judged by a lay jury.
Appeal
decision in the Gordon Wood case
A/Prof Rod Cross, Physics Department, University of Sydney
On 24th February 2012, three judges of the NSW Supreme Court acquitted Gordon Wood of the charge of murdering his girlfriend, Caroline Byrne. They concluded that the trial miscarried because the evidence was weak and largely circumstantial, the prosecutor overstated the case and that my evidence as an expert witness was flawed. As a result, they concluded that the charge of murder was not proven beyond reasonable doubt. The judgement was summarised in a 252 page document released on the day of the decision. It is a public document containing material that is strongly critical of my role as a scientist in the case, so I feel obliged to comment further.
The decision highlighted the
same fundamental flaw in the legal system that I pointed out above. The flaw
involves the double standard whereby judges can pass judgement on matters
outside their area of expertise, whereas experts are not permitted to comment
on matters outside their area of expertise. My own view is that matters of
science are best left to scientists to resolve, without interference from
others, especially in the first instance. However, I was told by a senior
barrister that if judges were required to have qualifications in fields on
which they pass judgement then the whole legal system would collapse. I was
also told by another senior barrister that if the press were to criticise
judges on their judgements then the public might lose faith in the justice
system. As a result, public criticism of judges is frowned upon, despite the
fact that judges are free to heap criticism on anyone they like.
The
judges quoted only one text book reference, and that was Starkie on Evidence, 3rd
ed., published in 1842. Standard physics textbooks did not rate a mention. The
judges could also have quoted the trial of Galileo in 1633 for declaring that
the earth revolved around the sun. Galileo�s book was banned and eventually
taken off the Vatican�s banned list in 1835. In 1992, the Vatican finally
conceded that Galileo was right. I don�t put myself in the same category as
Galileo but the legal situation is similar, indicating that it is still based
on the same medieval principle that judges know best. There is a backup system
whereby judgements can be appealed to a higher court, but in the Wood case the
DPP decided not to appeal to the High Court, without divulging reasons, so the
backup system backfired and the case ground to a halt.
The following specific
examples from the judgement illustrate some of the many instances where the
judges used their higher authority to prove that I got it wrong. In all, I
counted 170 factual mistakes made by the appeal judges. That was just
concerning my own evidence. There were too many to include them all in this
brief summary. I mention only one other mistake. The judges concluded that the
evidence of Mr Byrne was unreliable because he got a date wrong. It concerned
an event on Christmas eve when Renee Rivkin was supposed to have arrived back
in Australia and headed straight out to the Byrnes to play scrabble. The judges
said that wasn�t possible because evidence was presented that Rivkin returned
three days after Christmas. In fact, it was someone else who returned to play
scrabble. It was the judges who got their facts wrong, not Tony Byrne. It did
not concern them that the chance of Rivkin heading off to play scrabble on
Christmas eve with the Byrne family was about as remote as one could possibly
imagine.
1. When Caroline Byrne
landed at the bottom of the cliff she ended up with her legs pointing
approximately to the west or north west. I worked out from the nearest points
to the cliff, plus other factors, that she came from a ledge to the north. The
judges dismissed that evidence, saying that she must have come from the
direction where her legs were pointing. They ignored the fact that she landed
at 80 km/hr.
Photo taken from the north ledge showing a mannequin
in the position that Ms Byrne landed.
The
mannequin�s legs are not pointing straight to the north ledge but are angled
slightly away.
The
judges said that Ms Byrne must therefore have come from a point further around
the cliff top
and
that I deliberately ignored the leg position. I ignored it because it was of no
scientific value at all.
2. I conducted a throwing
test where the woman who was thrown remained limp, to simulate the effect of
throwing an unconscious woman. The judges dismissed that experiment as being
ineffective because the woman "facilitated her entry into the
water" by thrusting her arms forward.
However, she did that AFTER she was thrown. Throw speed has nothing to do with
what happens AFTER the throw. The woman even climbed out of the pool by
herself, after the throw.
The chief judge commented
that �To my mind all of this experimental
analysis must be approached with considerable reservation. The tests carried
out by A/Prof Cross were all conducted in daylight and in conditions where none
of the participants had reason to fear for their safety. The run up was secure
and the persons who were thrown were of course cooperative. One test was done where the female volunteer was asked to
remain limp. However, even in this experiment she cooperated and facilitated
her safe entry into the water.�
3. The judges preferred the evidence of the defence expert because he used "more sophisticated" equipment. They ignored the fact that his two subjects could apparently run almost as fast as the world champion sprinter "Flo Jo" from the 1980's. They failed to notice that he tested very good athletes, not females of average athletic ability, and they failed to recognise that a feet first jump results in a feet first landing, not a head first landing. Despite those serious omissions, the judge declared that �I am in no doubt that, because of the sophistication of his equipment, the tests conducted by [the defence expert] are more reliable.�
The judges also concluded that I �conducted a series of not particularly sophisticated experiments� that �involved strong men throwing women into swimming pools�. Given the uncertainty of the athletic ability of Ms Byrne and the wide range of athletic abilities of other females, it was not necessary to measure throw or jump or dive speeds to an accuracy better than about 2%. The equipment I used was perfectly adequate for that purpose and cannot be criticised as being unsophisticated. Furthermore, the experiments themselves did not need to be sophisticated. They were designed to measure typical run, jump, dive and throw speeds and to establish reasonable limits of performance in those tests. The judges made several errors of fact here. Only one woman was thrown, not several different �women�. And many more experiments were conducted to measure running, jumping and diving speeds.
4. The judges didn't like
my jumping and throwing experiments because "the conditions under which
his experiments were conducted were materially different to the conditions on
the night Ms Byrne died." The logical
conclusion is that I should actually have thrown women off the cliff on a cold,
dark night. They did not consider the fact that a cold, dark night would reduce
athletic performance rather than enhance it.
5. The judges claimed that �A/Prof Cross was satisfied that a strong, fit man could have thrown a woman of Ms Byrne�s weight from near the bend in the safety fence.� I never made that claim. In fact, I found that throwers were able to throw at sufficient speed by taking a few steps before throwing to avoid going over the edge themselves. Had they taken a long runup from the safety fence then they may have gone over the edge.
6. After I submitted my first report on the case, I asked the police if
they were certain that they had given me the correct landing spot and I asked
for photos of the landing spot since I had difficulty understanding the
surprising lack of injuries sustained in the fall. The police followed up by
arranging a visit to the site to help sort out those concerns. The judges
agreed that this was an example of me �actively participating in the making
of evidence directed to traversing of the existing forensic evidence which as a
consequence caused the trial to miscarry.� Scientists always double check and
retrace their steps in an attempt to ensure that their results are valid. The
judges and the defence should have been well aware of that. If not, then it
discloses deep ignorance of the way that scientists undertake their work.
Nevertheless, the judges concluded that �By the time he was able to revisit the
site, A/Prof Cross had become involved and was questioning whether the correct
location had been identified. A/Prof Cross� reasoning for doing so appears to
have no foundation other than perhaps out of concern to eliminate the possibility
of suicide, thus leaving open a prosecution for murder.�
7. Another physics mistake concerned the evidence that everyone gave
that the night was pitch black. The judges said that in that case, nobody would
run and throw a woman off the cliff because it would be too dangerous. I
checked the weather records and found it was cloudless on the night and the
moon set at 1 am. A scream was heard at 11:30 pm. People started arriving
aftert 2 am. The judges either ignored that evidence or were unaware of it, and
obviously didn't bother to check themselves. It didn't rate a mention in their
250 page report. That's one of the first things I checked. There were two
fisherman who arrived at about 10 pm and also said it was very dark. They were
fishing near a street light about 200 m away. They were the ones who heard the
scream. You can't see the ground very well or even the stars if you are
near a street light. If you move away from the light so it is hidden then the
ground is easy to see if the moon is up and the eyes get accustomed to the
dark.
8. The judges claimed that I �set about determining whether she could have been
thrown from the cliff.� That
conclusion was incorrect. My objective was to examine all the evidence to see
if it pointed to an accident or a suicide or a homicide, or indeed whether
insufficient evidence was available to make any such determination. My first
quick calculation in 1997 indicated that Ms Byrne had jumped. In 2003, having
performed some preliminary throwing and jumping experiments, I came to the same
conclusion. It was not until 2005, after many additional experiments, that I
concluded that she was thrown.
9. It was claimed that �However, he calculated that with the available run up it was possible for a strong man, using a �spear throw� technique to have thrown Ms Byrne to hole A without also falling off the cliff top as he threw her.�
There are several factual errors in that
sentence. The available runup was more than sufficient to take a few steps. The
available runup did not therefore limit the possible throw speed. Furthermore,
the danger of falling off the edge was not a theoretical calculation. It was
based on the experimental evidence.
10. The judges noted
that �In 2003, in a
walk-through interview with police, eight years after the event, Peter said
that the applicant was pointing in the direction of Pyramid Rock. That evidence
is somewhat troubling. If as all the evidence indicates it was a �pitch black�
night and the rocks could not be seen from the cliff top it would have been
difficult, if not impossible, to determine that the applicant was pointing to
pyramid rock.�
That is illogical and na�ve. Peter (Caroline�s brother) was with Wood at
the time. He could see Wood. He could see where he was pointing. He couldn�t
see the rocks below. But when he went back later, he could see the general area
to where he was pointing. The most obvious feature in that area is the Pyramid
Rock. So, one can assume that Peter told others later that Wood was pointing
toward the Pyramid Rock.
11. The judges commented that
�A/Prof Cross said that he had concluded that the �running speed� for 13
females aged 20 to 35 years after they had run 4 m ranged from 3.7-4.85 m/sec.
In his experiments one of the women tested would have achieved the speed to
dive to hole A. However, A/Prof Cross said that none of the police cadets could
have jumped to hole A.�
In fact, it was the other way
around. That is, none of the cadets could have dived to hole A. The judges failed
to understand the significance of the results, and thereby got it wrong. It is
quite a serious mistake, given that Ms Byrne landed head first.
12.
The judges commented that I have �no qualifications or experience in
biomechanics.�
That was
not correct. I have no formal qualifications in biomechanics, but have had
considerable experience working with biomechanists regarding sports research.
We have published joint papers. I have refereed many papers on biomechanics for
journal editors. Biomechanics is a field based on mechanics, which is properly
a field of physics. In any case, my measurements were simply those of running,
jumping, diving and throwing speeds, which can easily be obtained by standard
video analysis or radar gun measurements, commonly used by both physicists and
biomechanists. I even conducted a few measurements using a ruler, despite my
formal lack of qualifications in biomechanics.
13.
The judges commented that �Prof Fryer concluded that Ms Byrne�s shoulder
width ranged from 342 mm to 353 mm, most probably 345 mm�
The judges then quoted from my own report:
�The width of a female across the
shoulders is typically about 40 to 43 cm, while the incorrect cavity is about
40 cm wide at the top and narrows to about 30cm at the bottom.� A/Prof Cross�s assumption
was clearly wrong. It casts considerable doubt, at least on this aspect
of A/Prof Cross�s thesis.�
I
measured the shoulder widths of 16 females and they ranged from 350 mm to 390
mm with both arms up, and from 390 mm to 450 mm with both arms down, as
detailed in my report of 4 April 2008. Prof Fryer did not include the the full
width of the shoulders and both arms in his estimates of shoulder widths. The judges effectively concluded that
Ms Byrne did not have any arms, hence Prof Fryer was correct and I got it
wrong.
The
judges missed or misunderstood the whole point. That is, why were there no
injuries to Ms Byrne�s shoulders given that hole B was 1 m deep and narrowed to
300 mm at the base? Ms Byrne was wedged about 1 m deep up to her waist. The
answer is that she didn�t land in hole B. All the physical evidence, including
the dimensions of hole B, pointed to the fact that hole A was the correct
landing point. That evidence was presented to the jury at the trial. The judges
ignored all that evidence in their report and claimed that there was still some
doubt.
The
judges also commented on the mannequin that was used. The mannequin could not
fit firmly in hole B unless both arms were removed, reducing the shoulder width
from 365 mm to 330 mm. The judges overlooked that detail in coming to their
conclusions.
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