The Nature
of Evidence
A Guide to Legal Evidence & the Courts
Evidence: Any statement or
object from which conclusions
can be drawn
Circumstantial Evidence
Information that seems to point to
a perpetrator, including witnesses
& documents
Documents could be credit card
receipts, telephone records or
correspondence (mail or email)
Physical Evidence
Actual objects that are associated
with the crime & can be linked to
the perpetrator
Can include blood, hair, fibers,
DNA, etc.
Class Evidence
Evidence that can be linked to a GROUP of
people
Example: hair, fiber, blood type
Individual Evidence
Evidence that can be linked to ONE
individual person
Example: fingerprint, DNA
“Discovery”
Each attorney is required to submit
information regarding facts and
expert information BEFORE the
trial. This includes a list of
witnesses.
Science Admissibility Standards
Frye Standard
Federal Standard
Daubert Versus Merrell Dow
Frye Standard
The court must decide if the questioned
scientific procedure, technique, or
principles are “generally accepted” by a
meaningful section of the scientific
community
General acceptance is usually shown
through expert testimony,
books/documents/articles, as well as prior
judicial decisions
Federal Standard
More flexible than Frye Standard
Does not rely only on “general acceptance”
Describes expert testimony
Witness is considered an “expert” based on
knowledge, skill, experience or training
May testify if testimony is based on facts or data,
reliable methods were used, and the expert applied
them to the facts of the case
Daubert vs Merrell Dow
Landmark Supreme Court ruling (1993)
Judges in federal court must assume the role
of “gatekeeper” in the admissibility and
reliability of scientific evidence
Has the technique or the theory been tested
Has it been subject to peer review and publication
Potential rate of error
Standards controlling the technique
Widespread acceptance within the scientific
community
Expert Witnesses
An individual whom the court
determines possesses knowledge
relevant to the trial that is not
expected of the average person
Laws & Crimes
Law: codes of behavior with penalties
for infractions
Civil Law: lawsuits for injuries, traffic
violations, contracts, punishable by
fines
Criminal Law: punishable by fines, jail
time, community service, possible
death
Crime
Violation of a local, state, or federal law
Must have a “victim”, a “perpetrator” and a
“crime scene”
Misdemeanor
Minor crime
Punishable by fines & jail time of
less than one year
Examples: theft, minor assault,
license violations
Felony
Major crime
Punishable by larger fines & time
in prison
Examples: murder, rape, armed
robbery, drugs, fraud, auto theft
Locard’s
Exchange
Principle
Whenever 2 objects come in
contact with one another, there is
an exchange of trace materials
between them.