3. Relevance
Material - The evidence must relate to the case at
hand. Previous criminal records are not material, and they
can be prejudicial; as such, they are inadmissible.
Probativeness - The evidence must prove something. If
the evidence, such as the possession of a poison by the
accused, has no relevance to a death by strangulation, it is
inadmissible.
4. Competence
Prejudice - Anything that unduly affects the trier-of-fact in
an opinion either for or against the accused, is considered
prejudicial. Prior criminal records, or inflammatory images
may therefore be ruled inadmissible.
5. Competence
Constitutional Constraints - The 4th Amendment to the U.S.
Constitution states the following:
The right of the people to be secure in their persons, houses,
papers, and effects, against unreasonable searches and seizures,
shall not be violated, and no warrants shall issue, but upon probable
cause, supported by oath or affirmation, and particularly describing
the place to be searched, and the persons or things to be seized.
As such evidence obtained without a warrant, without probable
cause, and not listed in the warrant as the place, person, or thing
to be seized, is therefore inadmissible, regardless of relevance.
6. Constitutional Constraints
The following Amendments to the U.S. Constitution are
important in terms of criminal proceedings:
Amendment IV
The right of the people to be secure in their persons, houses,
papers, and effects, against unreasonable searches and
seizures, shall not be violated, and no warrants shall issue,
but upon probable cause, supported by oath or affirmation,
and particularly describing the place to be searched, and the
persons or things to be seized.
7. Amendment V
No person shall be held to answer for a capital, or otherwise
infamous crime, unless on a presentment or indictment of a
grand jury, except in cases arising in the land or naval forces,
or in the militia, when in actual service in time of war or
public danger; nor shall any person be subject for the same
offense to be twice put in jeopardy of life or limb; nor shall be
compelled in any criminal case to be a witness against
himself, nor be deprived of life, liberty, or property, without
due process of law; nor shall private property be taken for
public use, without just compensation.
8. Amendment VI
In all criminal prosecutions, the accused shall enjoy the right
to a speedy and public trial, by an impartial jury of the state
and district wherein the crime shall have been committed,
which district shall have been previously ascertained by law,
and to be informed of the nature and cause of the
accusation; to be confronted with the witnesses against him;
to have compulsory process for obtaining witnesses in his
favor, and to have the assistance of counsel for his defense.
9. Amendment VII
In suits at common law, where the value in controversy shall
exceed twenty dollars, the right of trial by jury shall be
preserved, and no fact tried by a jury, shall be otherwise
reexamined in any court of the United States, than according
to the rules of the common law.
Amendment VIII
Excessive bail shall not be required, nor excessive fines
imposed, nor cruel and unusual punishments inflicted.
10. Amendment XIV
Section 1. All persons born or naturalized in the United
States, and subject to the jurisdiction thereof, are citizens of
the United States and of the state wherein they reside. No
state shall make or enforce any law which shall abridge the
privileges or immunities of citizens of the United States; nor
shall any state deprive any person of life, liberty, or property,
without due process of law; nor deny to any person within its
jurisdiction the equal protection of the laws.
11. Competence
Statutory Constraints - This is also called "Privileged
Information," or information told to a person who cannot
reveal it (such as lawyers or clergy).
Hearsay - Hearsay is a statement made outside of court by
a person who was not under oath when the statement was
made, but is then being used as proof that the statement
was truth.
12. Frye Standard - 1923
Frye Standard (1923) During Frye's murder trial, he wanted
his blood pressure test results (a precursor to a lie
detector) used as evidence, but as it was not accepted by
the scientific community as a reliable test, it was not
admissible in court. The Frye Standard, or Frye Test, asks
1. Is the scientific theory generally accepted in the scientific
community?
2. Is the scientific method generally accepted in the scientific
community?
3. Has the technique been applied correctly?
13. Federal Rules of Evidence - 1975
Federal Rules of Evidence (1975),
Rule 702 was a bit more relaxed, stating that if the witness'
expertise helps the "trier of fact" to understand the evidence,
than a witness' testimony would be considered admissible.
14. Daubert vs. Merril Dow - 1993
Daubert vs. Merril Dow (1993) The Supreme Court decided that
it was the role of the trial court to be a "gatekeeper," and that
it's gatekeeping function was to make sure that scientific
testimony and evidence are reliable and relevant. The Daubert
Standard, or Daubert Test, asks:
1. Has the scientific theory or technique been tested?
2. Has the scientific theory or technique been subjected to peer
review and publication?
3. What are the known or potential error rates of the theory or
technique when applied?
4. Do standards and controls exist, and are they maintained?
5. Has the theory or technique been generally accepted in the
relevant scientific community?
15. Expert Witness
Forensic Evidence relies upon the testimony of expert
witnesses.
Expert witnesses are judged to be expert only by the
Judge her/himself. In order to be so judged, it is necessary
to have the appropriate training and experience (which
need not be a Ph.D.), as when a mechanic gives expert
testimony regarding a car involved in an accident.
A non-expert witness is called a lay witness.
16. Expert vs. Lay
Differences between an expert and a lay witness:
1. An Expert Witness must be qualified as an expert every
time she/he testifies in court.
2. An expert witness is permitted to offer opinions, whereas a
lay witness generally cannot.
17. Lab Reports
Although lab reports are technically an example of
hearsay, as the report itself cannot be cross-
examined. There are, however, exceptions: in some states
both sides can agree to admit it (stipulate), some states
require the author present, in some states it fits under a
business records exemption.
18. Defense vs. Prosecution
Innocent until proven guilty . . .Reasonable Doubt - The Prosecution
has the burden of proof. The defense has the responsibility to either
exonerate the accused, or at least to introduce a reasonable doubt.
Beyond aReasonable Doubt vs. No Doubt (The jurors must decide . .
.). There is no precise definition, so it is thus in the hands of the jury.
Defense must provide a spirited defense, regardless of the guilt or
innocence of the accused (or a mistrial can be called).
The Prosecution tries cases it can win (Winnability vs. The Desire to
Seek Justice)
19. Discovery Motions
The defense is required access to the witness list, as well
as to the evidence, so that it may carry out its own
evaluation of the evidence.
20. Chain of Custody & Evidence
Contamination
The chain of custody, if not carefully managed, not only
increases the risk of contamination, but it also can
introduce a reasonable doubt.
