[email protected] r.a. reiss interpretation and evaluation of evidence christophe champod...

[email protected]

R.A. Reiss

Interpretation and Evaluation of Evidence

Christophe Champod

School of Criminal Sciences / Forensic Science Institute

Faculty of Law and Criminal Sciences / University of Lausanne, Switzerland

SPSA / SPIR Annual Conference September 14-15, 2010

Acknowledgements: I. Evett, G. Jackson. S. Jones

–2– SPSA / SPIR Annual Meeting, September 14-15, 2010SPSA / SPIR Annual Meeting, September 14-15, 2010

State of AffairWillis SM. Forensic Science, Ethics and Criminal Justice. In: Fraser J, Williams R, editors. Handbook of Forensic Science. Cullompton, UK: Willan Publishing; 2009. p. 523-45.

Most efforts made within the scope of ISO/SEC

17025

Most efforts made within the scope of ISO/SEC

17025

A rather “laissez-faire” approach

A rather “laissez-faire” approach

Very important to distinguish between investigator and

evaluator role of the forensic scientist

Jackson & al. The Nature of Forensic Science Opinion […]. Science and

Justice. 2006;46(1):33-44.

Very important to distinguish between investigator and

evaluator role of the forensic scientist

Jackson & al. The Nature of Forensic Science Opinion […]. Science and

Justice. 2006;46(1):33-44.


Formulation of evaluative opinionAssociation of Forensic Science Providers. Standards for the Formulation of Evaluative Forensic Science Expert Opinion. Science & Justice. 2009;49(3):161-4.

This document may serve as a basis for all ENFSI laboratories.

Why not adopting it at EU level across all forensic disciplines ?

–4– SPSA / SPIR Annual Meeting, September 14-15, 2010FS in the 2010s – Northumbria University – 8.06.10SPSA / SPIR Annual Meeting, September 14-15, 2010

...because I have attempted toplace before the court all

of the data that may assist the jury.

Getting away from the God’s syndrome

Balanced

Logical

Fair

Scientific

‘Duty of care’

Transparent

« Know to doubt »Edmond Locard


Balance?

Forensic Expert Opinion

Logic?

If we can get the logic right – then this helps us to maintain balance


Somewhat recognized > NRC p. 186:

“ Publications such as Evett et al., Aitken and Taroni, and Evett provide the essential building blocks for the proper assessment and communication of forensic findings.”


Probability of theevidence given theprosecution case

Probability of theevidence given the

defence case

The single most important advance inforensic science thinking is the realisation

that the scientist should addressthe probability of the evidence

The ratio of these two determinesthe way that the scales of justice are

tilted by the scientific evidence


Work within a framework of background information

Need to consider at least two competing propositions

1

2

3 Need to consider the probability of the observations

Principles of evidence interpretation

Probability of the forensic findings if the prosecution’s proposition (Hp)

is trueProbability of the forensic findings if

the defence’s proposition (Hd) is true

LR =


Consequences of the framework>There is a need for an early identification of the issues

at hand (as identified by both prosecution and defence).

>More use of Part 33, Rule 33(5) of the Criminal Procedure Rules (United Kingdom), initiated after the Auld report (1991).

> In both Reed, Reed, & Garmson and in Weller, the UK Court of Appeal recently recognized its benefits.


Regina V. Denis John Adams (No.2), Court of Appeal - Criminal Division, [1997] EWCA Crim 2474


Circumstances>On the 6th of April 1991, Mrs M. is victim of an assault

and raped by an unknown individual. She desribed him as a caucasian male between 20 and 25 years old.

>A vaginal swab is taken for further investigation.

>A DNA profile is obtained and kept the MFSL database (before the NDNADB)

>Two year later, Denis John Adams is arrested for similar facts.

>His DNA profile matches the profile obtained from the vaginal swabs taken from Mrs M.

>D.J. Adams denies any involvement in the assault.


The match probability is 1 in 200 million

The match probability is 1 in 200 million

Match

ADN

D.J. ADAMS

Evidential value


Probability of the forensic findings if the prosecution’s proposition is true

Probability of the forensic findings if the defence’s proposition is true

What is the probability of getting such a profile if someone else is the source?

What is the probability to obtain this matching DNA profile given that D.J.

Adams is truly the source of the biological fluid?

This is the match probability

In this case, that value is

close to 1

LR=


1

Pr. Coïncidence fort.1 in 200 million

The results are 200 million times more likely if the biological fluid

originates from D.J. Adams than if it originates from un unknown

unrelated caucasian individual.

The results are 200 million times more likely if the biological fluid

originates from D.J. Adams than if it originates from un unknown

unrelated caucasian individual.

LR =

200 millionLikelihood

ratio =


the probability of getting such a profile if

someone else is the source?

Probability of the results given the

defence’s proposition (hd) is true

Critically depends on the circumstances of the case

Be transparent in our statements and ask ourselves:

•Is it sufficient to pick one option (e.g. unrelated)?•Why always taking the unrelated source as a default option?

1 in 200 million – unrelated 1 in 220 – siblings

Why this proposition ?

Transparent


Such as in this case:(1) The victim Mrs M. did not

recognize ADAMS(2) ADAMS had an alibi for that

day

Il will be the duty of the court to combine this element of scientific

evidence (DNA) with the rest of the probative elements in the case.

Is ADAMS the source of the sperm?


UK Court of Appeal rulings in relation to DNA evidence

>It is the duty of the expert to deal solely with the “random match probability”.

>The expert should not comment on the fact or probability that the defendant had been left the stain.

>The combination of the scientific evidence with the other evidence at hand should be left to the judgment of the jury (common sense) without any mathematical assistance.

R. v Doheny and G. Adams [1997] 1 Cr App R 369R. v D. J. Adams [1998] 1 Cr App R 377


R. V. Peter Weller, UK Court of Appeal, [2010] EWCA Crim 1085


The caseHp: Peter Weller began to stroke her body, her

breasts and her legs and had then inserted his finger into her vagina.

Hd: Peter Weller helped her into bed. He had checked her several times and on one occasion had had to put her into the recovery position. He had indeed had to pick up her clothes, including her knickers which she had left on the floor. He strongly denied the account of the sexual assault that she had given.

Directly from R. V. Peter Weller, UK Court of Appeal, [2010] EWCA Crim 1085


The forensic evidence> Medical evidence: the injuries were not accidental

and had not been caused by infection but because something blunt had penetrated her vagina. Fingers were the likely cause of those injuries.

> Nail clippings: The nails were swabbed and on the right hand there was only found a DNA profile for the appellant. On the left hand a full mixed profile was obtained. The major profile was that of the appellant but there was a minor full profile of another person; there is no dispute […]that the DNA in the minor profile was that of Emma.



Transfer>The four possibilities of primary transfer were:

1. From the appellant’s contact with the hair of Emma whilst moving her hair out of the way when she was vomiting or putting her to bed.

2. Touching Emma when putting her into bed or holding her in the recovery position.

3. Contact with vomit.4. The insertion of fingers into her vagina.



‘Evaluator’

Did he do the activity?

Has he committed the offence?

Is this reference sample the source of the trace material?

What are the activities leading to the recovered DNA?

Who is the source of the DNA? (not disputed in this case)

Hierarchy of propositions


The added value of the forensic statement is increased when we operate higher in the hierarchy

Added value

Source

Activity

Offence

Moving up the hierarchy requires more data and specific

knowledge

Specificknowledge

To progress, you need more context information

Context information



At the first trial

It provides strong scientific support for the view that the

source of the DNA was contact with the vagina.

It provides strong scientific support for the view that the

source of the DNA was contact with the vagina.

Prosecution expert

Defense expert

The evidence is more likely to be seen given that scenario than other scenarios. […] well I have in mind what strong means in terms of the scale, and I think that’s setting it too high.

The evidence is more likely to be seen given that scenario than other scenarios. […] well I have in mind what strong means in terms of the scale, and I think that’s setting it too high.


The Appeal

However experienced someone is, the state of the science is not such that an

evaluative judgment could be expressed.

However experienced someone is, the state of the science is not such that an

evaluative judgment could be expressed.


The outcome

>A court in determining whether there is a sufficiently reliable scientific basis for expert evidence to be given and a jury in evaluating evidence will be entitled to take into account the experience of experts and, if their experience is challenged, to test that.


It is not a blank

check !

It is not a blank

check !


R. V. Barry George, UK Court of Appeal, [2007] EWCA Crim 2722


Evening Standard 15th November 2007


At 1130 on 26 April 1999, Jill Dando, a well-known TV personality was shot dead on the doorstep of her home in London.

There were no

witnesses

There was a single shot to the

head

No firearm was found

Barry George was interviewed on 11 April 2000His flat was searched and various exhibitswere taken for examination

A single particle of firearms discharge residue (FDR) was found in an inside pocket of his coat

The composition of the FDR particle was indistinguishable from FDR particles at the crime scene.

SEM/EDX


‘Evaluator’

Did he do the activity?

Has he committed the offence?

Is this reference sample the source of the trace material?

What are the activities leading to the recovered FDR?

What it a particle of FDR? (not really disputed)



The judge’s summing-upfor the juryAre you sure that

this is a particle of FDR?

[Adapted from Evett, 2009]

Are you sure that the particle was not deposited as a result of “innocent” or adventitious contamination?

YES

NO

NO

…then discard this evidence altogether; it will not help you at all. In that event, you may think this removes an important part of the Crown's case.

…. then you can take this matter into account

YES


As to whether the risk of that having occurred was real, theoretical or low risk, the experts vary in their individual assessments...

Summing-up:continued

In relation to this question of contamination, all the experts agree that there is a possibility that contamination could have occurred innocently.

... you must decide whose evidence you accept and whose you do not.

[Adapted from Evett, 2009]


The defence say ‑‑ that it is incredible, after one year, that it can be said that this is incriminating evidence. Particles are shed rapidly, and could not survive on the coat that long.

The Crown say –– that the particle, together with all the other pieces of evidence, overwhelmingly supports the Crown's case.

[Adapted from Evett, 2009]Summing-up:continued


Hp: Barry George is the person who shot Miss Dando.

Hd: Barry George had nothing to do with the incident.E: one

fragment of FDR was found

Expert’s view

What evidence do we expect to find if Hp is true?

What evidence do we expect to find if Hd is true?

Applying the framework

Probability of E if Hp is true:

very small

Probability of E if Hd is true:

very small

LR = 1


The outcome> It is clear from these extracts that the summing up

that the jury were directed that the evidence of Mr Keeley and Dr Renshaw provided significant support for the prosecution’s case that the appellant had fired the gun that killed Miss Dando. The judge did not consider that their evidence on this topic was ‘neutral’.

> In the light of the way in which Mr Keeley now puts the matter, we have no doubt that the jury were misled upon this issue.

Directly from R. V. Barry George, UK Court of Appeal, [2007] EWCA Crim 2722


Consequences

>Managing the transition from source level to activity level is too difficult to allow:

1) Leaving it to the court – it is part of the expertise

2) Leaving it to the expert on the D-day in court.

>Give precedence to written reports.


Future of “individualisation” ?

A footwear mark example

All other types of “categorical” evidence (handwriting, fingerprints, toolmarks, firearms, physical fit, etc..) can be treated by analogy


The challenge> Saks MJ, Koehler JJ. The individualisation Fallacy in Forensic

Science Evidence. Vanderbilt Law Review. 2008;61:199-219.

> Saks MJ, Faigman DL. Failed Forensics: How Forensic Science Lost Its Way and How It Might Yet Find It. Annual Review of Law and Social Science. 2008;4(1):149-71.

> Cole SA. Forensics Without Uniqueness, Conclusions Without Individualization: the New Epistemology of Forensic Identification. Law Probability and Risk. 2009;8(3):233-255.

> Kaye DH. Probability, Individualization, and Uniqueness in Forensic Science Evidence: Listening to the Academies. Brooklyn Law Review. 2010; to appear.


All shoes on Earth

Identification process: probabilities

“Earth population paradigm”

“Leap of faith” (D. Stoney)

SWGTREAD – Definite conclusion of identity : This opinion means that the particular shoe or tire made the impression to the exclusion of all other shoes or tires.

Weight of the FWM evidenceID decision – An adventitious match is a practical impossibility

1/all soles 99.99…%LR for FW evidence??


All shoes on Earth

Identification process: Decision

Weight of the FWM evidence

• Biedermann A, Bozza S, Taroni F. Decision theoretic properties of forensic identification: Underlying logic and argumentative implications. Forensic Sci Int. 2008;177(2-3):120-32.

Ground truth: John Doe’s sole left the mark

Identification decision Exclusion decision No decision (Excl/ID)

1x -10x -0.5x

Ground truth: An unknown sole left the mark

Identification decision Exclusion decision No decision (Excl/ID)

-5000x 1x -0.5x

–41– SPSA / SPIR Annual Meeting, September 14-15, 2010Impression and Pattern Evidence Symposium August 2-5, 2010

What is expert A doing?

1. Implicitely assigns prior probability2. Assesses the weight of the evidence3. Obtains the posterior probability4. Makes an decision according to an implicit

utility functionWe can argue that only 2) should be the remit of the forensic scientist and that steps 1), 3) and 4) are the duty of the court.

We can argue that only 2) should be the remit of the forensic scientist and that steps 1), 3) and 4) are the duty of the court.

–42– SPSA / SPIR Annual Meeting, September 14-15, 2010Impression and Pattern Evidence Symposium August 2-5, 2010

Once you understand the

process,

and concentrate only the evidence

You will abandon the concept of

individualisation

You will abandon the concept of

individualisation

Consequences


Conclusions> Interpreting evidence requires adopting a logical and

balanced framework.

> It requires that propositions are put forward by the parties, ideally before getting the results of the forensic examinations.

> Forensic scientists are more and more asked to guide in relation to alleged activities more than in relation to alleged sources.

> Statements will have to provide detailed guidance at activity level. There is nothing wrong in relying on experience as long as it can be logically and empirically tested.

> The days of conclusions of individualisations (meaning to the exclusion of all others) are counted.

[email protected] r.a. reiss interpretation and evaluation of evidence christophe champod...

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