Reporting forensic science results to court

Question 1

LO

Answer 1

*** What makes evidence ‘expert’
* Fact and opinion
* Duties on experts
* Principles of forensic science interpretation
* Reports and statement
* Expert evidence gone wrong **

Question 2

What makes evidence ‘expert’?

Answer 2

• Admissibility principles
• Fact and opinion
• Duties on experts
• Read the further reading documents listed on ppt

Question 3

Admissibility of expert evidence?

Answer 3

**Admissibility of expert evidence **
* Expert evidence is admissible: “to furnish the court with scientific information which is likely to be outside the experience and knowledge of a judge or jury”

• So…
  o It is only admissible when it is required
  o It can only be given by a person who is an expert in the relevant field
• See also:
  o National justice Cia Naviera SA v. Prudential Assurance Co. Ltd (The Ikarian Reefer) [1993] 2 Lloyd’s Rep 68, 81-82; [1993]
  o R v. Barnes [2005] EWCA Crim 1158
  o R v. Harris & Ors. [2005] EWCA Crim 1980
• EWCA= England and Wales court of appeal

Question 4

Opinion vs Fact

Answer 4

• Opinion is generally not admissible as evidence… except for expert opinion
• But sometimes experts also give opinion of fact
• Being able to tell the difference between fact and opinion is critical

Question 5

Is each of these statements fact or opinion?

• ‘I search the hard disk with tool X and determined that it contains no files containing text Y’
• ‘I search the hard disk with tool X and the tool found no files containing text Y’
• ‘The sample contained more THC than the legal limit’

Answer 5

• ‘I search the hard disk with tool X and determined that it contains no files containing text Y’:it is opinion
• ‘I search the hard disk with tool X and the tool found no files containing text Y’: It is fact
• ‘The sample contained more THC than the legal limit’: It is opinion

Question 6

Obscured inference

Answer 6

• I have performed data extraction using the tools set out in table A and obtained the observations in table B. there were no communications between Mr A and Mr B.’ A series of statements of fact? Opinion throughout as they only know that their extraction and analysis procedure did not find any communications between Mr A and Mr B

Question 7

Flawed logic

Answer 7

• I am an expert in fingerprint comparison
• I have declared that this mark and this print match
• Therefore, they match
• So, statement that they match is fact
• The logic is circular…. As the person making the statement doesn’t know the origin of the mark, so the statement must be opinion

Question 8

What is the over-riding objective of the criminal justice system?

Answer 8

o Acquitting the innocent
o Convicting the guilty
o Dealing with the case efficiently and expeditiously
 This includes obligations on all parties to play their part in effective case management
 CPR 1.1 and 1.2

Question 9

Case management: Crim PR 3

Answer 9

• CrimPr 2020, as amended January 2023
• The court must further override objective by actively managing the case

o The includes ensuring the evidence, whether disputed or not, is presented in the shortest and clearest way
* The parties must actively assist the court in fulfilling its duty under rule 3.2

Question 10

Objectivity and impartiality

Answer 10

• An expert witness must provide the court with objective, unbiased opinion on matters within his/ her expertise
• Examples from courts:
  o Obligation to the court over-rides obligation to the instructing party
  o Must disclose any potential conflict of interest i.e., payment based on case outcome
  o Must not assume role of advocate or jury
  o Must state facts and assumptions on which opinion is based
  o Must state range of opinion and reason for own opinion- courts brought in due to the controversy surrounding shaken baby cases
  o Assessment and use of scientific theories must be objective

Question 11

Honesty and good faith

Answer 11

• Witness must act with honesty and good faith
• Examples from courts:
  o The witness must act with honesty and must not mislead, or risk misleading, the court
  o The witness must not impugn the integrity of other witnesses without sound evidence

Question 12

Reasonable skill and care

Answer 12

• The witness must exercise reasonable skill and care and comply with relevant professional code of ethics
• Examples in courts
  o In analysis/ work undertaken
  o In use of research/ source papers
  o In preparing reports
  o In presenting evidence to assist the jury
  o Get the report peer reviewed

Question 13

Explanation

Answer 13

• CrimPr 19.4(h) states that the experts report must “include such information as the court may need to decide whether the expert’s opinion is sufficiently reliable to be admissible as evidence”
  o Not “trust me I’m a forensic scientist”
• The expert must explain their conclusions

Question 14

Disclosure

Answer 14

• Golden rules
  o Record
  o Retain
  o Reveal
• In particular, the expert needs to disclose:
  o Any information which would undermine their evidence
  o Any reservations in relation to their evidence
  o Whether any theory employed is well established or not
  o Any information which would support the case put forward by the defence
  o Any information which would undermine their credibility
• In England & Wales, the disclosure rules are primarily on the prosecution
  o See also CPS disclosure manual
• But:
  o General obligations on experts and requirements for objectivity and impartiality mean that all experts need to pay attention to their obligations to disclose material that might undermine their evidence in anyway
• Transparency

Question 15

Crim PR Part 19: Expert evidence

Answer 15

Question 16

When does interpretation start?

Answer 16

• After you have all your results?
• Or before you have even started to analyse?
  1. Reviewing the nature of the expert evidence being requested;
  2. Establishing the key issue(s) to be addressed;
  3. Determining what examinations and analyses are required;
  4. Commissioning those examinations and analyses;
  5. Interpreting the observation;
  6. Writing a report; and
  7. Appearing in court

Question 17

Case assessment and interpretation model

Answer 17

Question 18

Hierarchy of issues

Answer 18

Question 19

Stages

Answer 19

• Acquire information relevant to:
  o The issues to be addressed by the scientist
  o The choices of forensic strategy
• Clarify and define the instructing party’s requirements
  o What are the real issues in the case?
  o To what level in the hierarchy does each relate?
   Formulate mutually exclusive pair(s) of propositions
• Determine examination strategy
  o Consider for each technique, the probability of obtaining a range of observations, predicated on each of the propositions being true
  o What tests would you do to support the defence/ prosecution proposition. A good anti-biased approach
• Conduct the examination
• Interpret the findings

Question 20

Principles

Answer 20

Question 21

The likelihood ratio

Answer 21

Question 22

Data, knowledge, and judgement

Answer 22

• Data= information, consisting of observations, measurements, or facts
• What data do I have access to?
• How relevant are the data?
• What limitations are presented by the size of the data set?
• I want to assess the probability of observing a few sperms heads on a slide from a complainant, 4 days after intercourse in a case this year
• I have a paper from the 1980s describing the persistence of semen in the vagina at given times since sexual intercourse
  o What factors might influence the relevance of the data to my case?- its old data so techniques have changed for extracting sperm cells from a swab, quality of the sample i.e., sperm count has decreased by 50% since the 1980s, type of sample it was i.e., HVS or cell sample, all these things give data but not necessarily a perfect set of data
• I am investigation the cause and origin of a fire
• I know that wind direction and ventilation have a marker impact on fire spread patterns
  o What data might I access?- wind data
  o What other factors might have an impact?- what floor you’re are on etc
  o Be transparent in limitations in data which can limit findings

Question 23

Limitations and transparency

Answer 23

Question 24

Validation of interpretation methods

Answer 24

Question 25

Evaluation and conclusions

Answer 25

Question 26

Conclusions

Answer 26

Question 27

Categorical opinions

Answer 27

Question 28

Reporting against legal limits

Answer 28

• Police pull over a motorist and suspect they are under the influence of drugs
• Legal limit for ∆9-THC is 2µg/L
• Courts want to know if the motorist was over the limit when they were stopped
• Analytical results= 2.2µg/L
• Was the motorist over the limit?

Question 29

All notes on the following are within the lecture notes:
Reports and Statements
Expert evidence gone wrong