Evidence

What is evidence?

• In the law evidence can be broken down into two categories…– Direct evidence– Physical evidence

Direct evidence

• Direct evidence is made in the form of a statement made under oath, such as a witness pointing out a person that they believe committed a crime

• We also call this testimonial evidence

Physical evidence

• Physical evidence is any object or material that is relevant to a crime including small and large tangible objects, and/or smells and odors.

• This evidence is collected by the CSI then processed by a lab technician

Why is it important?

• Physical evidence can…– Prove a crime has been committed– Corroborate testimony– Link a suspect with a victim or crime scene– Establish the identity of associated persons– Allow reconstruction of events at a crime

• Evidence can also be broken down more by how much “weight” it carries in court proceedings.

Indirect evidence

• Indirect evidence is evidence that does not prove a fact; it only establishes a hypothesis based on facts…most evidence falls into this category

Circumstantial evidence

• Circumstantial evidence implies a fact or event…such as possession of narcotics

• The greater the volume/amount of circumstantial evidence there is the more likely it is that it is factual (probability and statistics.

What is good evidence?

• The rules of evidence define what evidence is admissible and what evidence is not

• Material evidence is all evidence that is relevant to a particular crime

• Evidence that proves something in a case is what we call probative.

• You want to convict someone then you better have material evidence that is probative

Inadmissible evidence

• Hearsay is a form of evidence that is not permissible in court because the person was not under oath when the statement was made

Credibility

• The expert witness is the person that is the expert in the field of science…they are the presenter of information in court

• Credibility is established through credentials, background, and experience in the topic.

What makes it admissible?

• There are two court rulings that have largely governed the admissibility of evidence in court– Frye vs. the United

States– Daubert vs. Merrell

Dow Pharmaceutical, Inc.

The Frye Standard

• The Frye standard states that in order to be probative– Testimony must be given by an expert

witness– The techniques used must have gained

general acceptance within its own field

The Daubert Ruling

• The Daubert ruling stated that the Frye standard was not an absolute prerequisite for admissibility in court, and that it was the judge that was responsible for determining validity

• The Frye standard was to be used only as a guideline

Why did it change?

• The Daubert ruling changed the previous Frye standard to help keep up with technological advances in the field.

• The guideline is:– The technique or theory must be testable– The theory must be subject to peer review– Potential error, and rate of error must be stated– The techniques must follow a standard– Consideration of the widespread acceptance, or lack

of, within the scientific community must be taken