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 StandardThe court must decide if the questioned scientific procedure, technique, or principles are “generally accepted” by a meaningful section of the scientific communityGeneral acceptance is usually shown through expert testimony, books/documents/articles, as well as prior judicial decisions

Federal StandardMore flexible than Frye Standard

Does not rely only on “general acceptance”

Describes expert testimonyWitness 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 DowLandmark 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 testedHas it been subject to peer review and publicationPotential rate of errorStandards controlling the techniqueWidespread acceptance within the scientific community

Expert WitnessesAn individual whom the court determines possesses knowledge relevant to the trial that is not expected of the average person

Laws & CrimesLaw: codes of behavior with penalties for infractionsCivil Law: lawsuits for injuries, traffic violations, contracts, punishable by fines Criminal Law: punishable by fines, jail time, community service, possible death

CrimeViolation of a local, state, or federal law

Must have a “victim”, a “perpetrator” and a “crime scene”

MisdemeanorMinor crime

Punishable by fines & jail time of less than one year

Examples: theft, minor assault, license violations

FelonyMajor 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.