What is Forensic Science?
the application of science to law
What is the scientific method?
process that ensures careful systemic collection, organization, and analysis of information
Describe the scientific method model
- begins by formulating a question worthy of investigation
- investigator then formulates hypothesis (a reasonable explanation to proposed question)
- followed by testing the hypothesis through experimentation (must be recognized and accepted by investigators) and analyzing data
- becomes scientific evidence
What is the difference between Science and Police driven investigations?
Science: follows scientific method, has a long history, and derived from pure science
Police: newer history, answers a specific question, developed out of specific police need
Forensic Scientist vs. Crime Scene Officer
Forensic Scientist:
- works in crime lab
- are scientists or civilians
- analyze evidence, submit report, testify
Crime Scene Officer:
- police officer
- identification specialists
What are 2 types of Forensic Bias
- Motivational Bias
- conscious but unintentional (favouring particular party) - Cognitive bias
- unconscious (seeing what you expect to see)
What are the different types of Cognitive Bias?
- Contextual Bias
- extraneous information - Confirmation Bias
- judgement is influenced by knowledge about other examiner’s decision - Selection Bias
- leaving out evidence on purpose - Expectation Bias
- one’s expectations about the results influence their judgement
List in order the different forensic labs that evidence goes through
- Evidence Management Section
- first place evidence comes in, is tagged, given ID # - Evidence recovery unit
- evidence is isolated and extracted before distribution - evidence can be sent to many labs depending on what needs analyzing:
- Forensic Biology, Toxicology, Chemistry, firearms/toolmarks, documents, digital
What are the 2 types of witnesses?
- Eye Witness
2. Expert Witness
Eye vs. Expert Witness
Eye Witness: - lay witness (witnessed crime) - cannot give opinion - not reliable Expert: - did not witness crime - gives opinion (unbiased) - has more knowledge than the average person on a specific topic - qualified by judge
How can an expert testimony be misleading?
- inadequate qualifications
- distort/omit knowledge
- misquote texts
- false statements
Frye Standard (Frye v. US)
the science or expert’s opinion must be generally accepted by the relevant scientific community and well established
Federal Rules of Evidence
- does not rely on general acceptance as a prerequisite for scientific evidence
- focuses on reliability of expert witness
Daubert Standard (Daubert v. Merrill Dow Pharmaceuticals)
- states Frye standard is not an absolute prerequisite
- assumes judge as gatekeeper in determining if evidence is admissible and reliable
(is it testable, are there error rates, are there standards for applying theory or technique so experiment is duplicatable, subject to peer review, generally accepted)
R. v. Mohan Rules of Evidence
- expert evidence must be relevant to case, necessary to assist trier of fact, doesn’t trigger exclusionary rule, and presented by qualified expert
Dulong v. Merrill Lynch Canada Rules of Evidence
- judge is deemed gatekeeper
What is the CSI effect?
- TV shows often exaggerate and dramatize forensic science which consequently may affect jurors evaluation of evidence
What is backlog?
- major problem for forensic DNA
- many cases occurring in the US and DNA analyses cannot keep up with demand
- backlog is unanalyzed DNA samples from crime scenes
How is biological sciences an issue in FS?
- techniques for DNA typing are judged
- challenges with mixtures and transfers of DNA
What are some issues with pattern evidence?
- no defined threshold for matching points
- no studies associated with matching characteristics with probability that impression came from same source
Why are bite marks an issue in FS?
- uniqueness of human dentition not established
- ability of skin to maintain bite pattern not established
- challenges distinguishing human bite marks to animal bite mark
- high error rates
Why is hair analysis an issue in FS?
- most cases end in wrongful conviction because of this method
- process is questionable
why are questioned documents an issue in FS?
- handwriting contains natural variation
what are some issues with explosives and fire investigations?
- arson is based on ‘rule of thumb’ and ‘experience’
- practical experiments show correct techniques are incorrect
