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Lay and Expert A person becomes a potential witness by having personal knowledge about the facts of a case to be tried. Personal knowledge may have been acquired ... – PowerPoint PPT presentation

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Title: Witnesses

WitnessesLay and Expert
  • A person becomes a potential witness by having
    personal knowledge about the facts of a case to
    be tried. Personal knowledge may have been
    acquired through something seen, heard, smelled,
    or touched.

A Law Enforcement Officer as a Witness
  • A law enforcement officer who is called as a
    witness usually has gained knowledge through
    individual investigation of a case or a certain
    portion of the case.
  • Most often, is a Lay Witness.

General Information on Witnesses
  • Witnesses are called upon during the course of a
    trial to relate their particular knowledge.
  • Witnesses are seldom surprised when they are
    called to testify, especially in criminal cases,
    because preceding most trials, law enforcement
    officers conduct extensive investigations and
    usually advise those they interview that they may
    be called.

The Reluctant Witness
  • Although many people willingly serve as
    witnesses, others, for a variety of reasons,
    serve reluctantly
  • Some wish not to become involved some fear
    reprisal others fear cross-examination.
  • Still others may wish to cooperate but are
    reluctant to lose time at work.

Compelling the Testimony
  • An individual does not always have a choice
    whether or not to appear as a witness.
  • Anyone with information that may be of value in
    arriving at the truth in a trial may be compelled
    to be a witness.
  • This power to compel a witness to attend a trial
    is based on two clauses appearing in the Sixth
    Amendment to the Constitution of the United
    States the Confrontation and Compulsory Process

The Confrontation Clause
  • The Confrontation Clause provides that "the
    accused shall enjoy the right . . . to be
    confronted with the witnesses against him" and
    the Compulsory Process Clause states that "the
    accused shall enjoy the right . . . to have
    compulsory process for obtaining witnesses in his
  • Both of these rights are available to the accused
    in federal and state trials.

The Confrontation Clause
Attendance of Witnesses
  • In order to ensure that a witness appears to
    testify, most lawyers will compel witnesses'
    attendance by issuing a subpoena.
  • A subpoena is an official document issued by
    either a judge, the clerk of a court, or an
    attorney and delivered to, or "served upon," the

Attendance of WitnessesIn Criminal Cases
  • In criminal cases, the subpoena sets forth the
    name of the defendant to be tried, the name of
    the person to be the witness, and orders the
    person to appear at a specific time and place and
    to remain in attendance until released.

Subpoena Duces Tecum
  • If the person has papers, records, or other
    physical evidence needed for the trial, the
    person will be served with a subpoena duces
  • This subpoena also directs the person to bring
    specific material to court.

Witnesses Failure to Appear
  • If a witness does not appear in accordance with
    an oral request, it is not a violation of a court
    order, and no penalty can be imposed.
  • A witness's failure to appear in response to a
    subpoena, however, is a violation of a court
    order and subjects the violator to the full range
    of judicial sanctions

Available Court Sanctions
  • There can be severe consequences for failing to
    honor a subpoena or subpoena duces tecum.
  • Criminal Contempt. Sanctions for criminal
    contempt of court can be a monetary fine,
    imprisonment, or both.
  • If the court chooses to imprison the person, the
    imprisonment will be for a fixed period of time
    and may continue even if the person later submits
    to the court's authority.
  • Should a person answer a subpoena but
    intentionally refuse to give testimony or produce
    the thing ordered, the court may find the witness
    in Civil Contempt.
  • The court may order the uncooperative witness
    placed in jail until the witness complies with
    the orders of the court.

Methods of Subpoenaing Witnesses
  • In most jurisdictions (California included), the
    attorneys (either the defense attorney or the
    prosecutor), issue their own subpoenas to compel
    the appearance of a witness.
  • In a few jurisdictions, the clerk or judge must
    issue the subpoena and the attorneys' duty is to
    furnish a list to the clerk of persons who are
    needed as witnesses.

Serving of the Supoena
  • Although in most states anyone may serve a
    subpoena, in criminal cases the subpoenas are
    usually given to an officer of the court, who may
    be a deputy sheriff, a constable, or a marshal,
    to be served on the person named in the
  • Registered Process Servers

Proper Service
  • The service of the subpoena consists of
    personally handing the subpoena to the person.
    In some jurisdictions, sending the subpoenas by
    certified mail or leaving the subpoena at a
    witness's home or place of work may be acceptable
    as proper service.

The Civic Duty to Testify
  • It is the duty of all persons to testify when
    needed. Organized society is based on the civic
    contribution of its members.
  • It is also considered to be an inherent right of
    our courts to compel a person to appear as
  • Few circumstances will excuse anyone from
    attendance as a witness, because the needs of the
    criminal justice system must be met and the
    convenience of the witness is of little

Out-of-State Witnesses
  • A subpoena is valid only within the state in
    which it is issued. Consequently, in the past,
    when a material witness in a criminal trial
    resided in another state, compelling an
    appearance created an obstacle.

Uniform Act to Secure the Attendance of Witnesses
  • This act permits a court to issue a subpoena to
    an out-of-state witness and to have the subpoena
    sent to a court in that state.
  • The witness will be commanded to appear in that
    court, where a hearing will be held to determine
    whether he or she is a material witness.
  • If it is determined that the witness is material,
    he or she will be ordered to appear in the court
    where the original subpoena was issued.
  • A witness who fails to appear as ordered may
    suffer the same contempt sanctions as a witness
    within the state.
  • Witnesses may be entitled to compensation for

Segregation of Witnesses The Rule on Witnesses
  • The reason for segregating or excluding the
    witnesses is to prevent witnesses from hearing
    each other's testimony and being affected by it,
    either intentionally or unintentionally.
  • The rule on witnesses is designed to prevent the
    most overt form of witnesses' collaboration.

The Rule of WitnessesJudicial Admonishment
  • Judges will also direct witnesses not to discuss
    their testimony among themselves while waiting to
    appear in the courtroom.
  • Of course, this does not keep witnesses from

Two Categories of Witnesses
  • Witnesses have been classified into two
  • (1) the lay or ordinary witness and
  • (2) the expert witness.

Lay or Ordinary Witness
  • The lay witness is a person who has some personal
    knowledge about the facts of the case and who has
    been called upon to relate this information in
  • The law enforcement officer will usually fall
    within the category of the lay witness.
  • The lay witness is permitted to testify about
    facts only, and, with few exceptions, may not
    state personal opinions.

Methods ofInterrogating Witnesses
  • With respect to direct examination, the Federal
    Rules of Evidence have taken the traditional view
    that it is improper for an attorney to ask
    leading questions of the witness.
  • Unless an exceptions applies, direct examination
    must be by non-leading questions.

Questioning the Witness
  • A leading question is one that suggests to the
    witness the answer sought by the questioner.
  • The law prefers open-ended, or non-leading,
  • Suggestive questions could induce a witness to
    inadvertently adopt the questioner's suggestion.
    This is especially likely where the attorney
    posing the leading question prepared the witness
    to testify and the witness has some relationship
    with the party represented by that attorney.

Statutory Guidelines
  • FRE provides for exceptions to the rule
    prohibiting leading questions on direct
  • 1) with respect to undisputed preliminary or
    inconsequential matters
  • 2) when a witness is hostile, unwilling,
    frightened, or biased
  • 3) with respect to a child or adult witness with
    communication problems
  • 4) with a witness whose recollection is
    exhausted and
  • 5) when laying a necessary foundation under
    certain circumstances.

Witness InterrogationThe Narrative Form
  • In this method, the witness is requested to state
    in his or her own words what happened in a
    particular instance.
  • This permits the witness to tell the story in a
    logical sequence, and it is undoubtedly easier
    for the jury to follow evidence presented in this

Caution!The Narrative Questioning
  • The witness, not being fully informed on the
    rules of evidence, may testify concerning many
    things that are incompetent, irrelevant, or
    inadmissible, bringing objections by the opposing
    side and requests to strike the testimony from
    the record.
  • The judge must then admonish the jury to
    disregard the testimony.
  • While telling his or her story, the witness may
    go into matters the attorney did not intend to
    include at that particular time.
  • Or the witness may include irrelevant material,
    which would result in extensive cross-examination
    and could be detrimental to the case.

Cross-examination and the FRE
  • FRE 611(c) says "Ordinarily leading questions
    should be permitted on cross-examination."
  • No question may be asked on cross-examination
    unless it the subject has been brought up during
    direct examination.

The Benefits of theCross-Examination
  • Cross-examination is an indispensable method of
    either eliciting testimony favorable to the
    examiner's case or impeaching the witness's
  • In eliciting favorable testimony, an attorney on
    cross-examination might simply seek to have the
    witness testify to disputed facts favorable to
    the examiner's case.
  • The attorney could have the witness repeat
    favorable testimony already stated on direct
  • The cross-examiner might try to get the witness
    to qualify or explain damaging testimony given
    during direct examination.

Pitfalls Concerns on Cross-Examination
  • Usually the witness under cross-examination is an
    adverse witness (one aligned with the other
    side), who may, because of a conscious or
    unconscious hostility engendered by the
    cross-examination, take advantage of the
    situation and try to volunteer additional
    information to the advantage of the opposing
  • This is an ever-present hazard of
    cross-examination, both for the witness and the

Cross-ExaminationsPrimary Benefit Impeachment
  • The most important purpose of cross-examination
    is to persuade the jury to disbelieve the
    testimony of a witness, to impeach the witness.

  • Impeachment is a process or a result that
    diminishes the believability of a witness's
    testimony or destroys it. There are five basic
    methods of impeachment
  • (1) by contradiction
  • (2) by proof of bad character for truthfulness
  • (3) by proof of prior inconsistent statement
  • (4) by proof of bias or motive to falsify and
  • (5) by proof of lack of or diminished witness

Methods of ImpeachmentContradiction
  • Impeachment by contradiction consists of asking
    the witness about facts that are directly in
    opposition to those testified to on direct

Crimes of Bad Characterfor Truthfulness
  • The crimes that can be shown to impeach for bad
    character for truthfulness are
  • Any crime punishable by imprisonment in excess of
    one year (Felony).
  • A crime involving dishonesty includes perjury,
    fraud, or embezzlement.

Impeachment byBad Character for Truthfulness
  • Impeachment by proof of bad character for
    truthfulness can be done in only two ways.
  • First, the witness can be impeached by proof that
    he or she was convicted of certain crimes.
  • Second, the witness can be impeached by
    questioning on cross-examination about specific
    bad acts that involve dishonesty but did not
    result in a conviction.

Impeachment by Prior Inconsistent Statement
  • Impeachment by prior inconsistent statement
    consists of the cross-examiner asking the witness
    about the fact that the witness previously made
    statements contradicting the testimony given on
    direct examination.

What is acontradictory statement?
  • If a witness has made contradictory statements,
    the jury might think that the witness is either
    mistaken or lying, or has changed his or her mind
    for some other reason.
  • The only requirement in most states for the
    cross-examiner to prove the content of a prior
    inconsistent statement is that the witness be
    given an opportunity to explain or deny the
    statement and the opposing party be afforded an
    opportunity to interrogate the witness about the

Impeachment for Bias
  • Impeachment for bias may take many different
    forms. Any interest the witness may have in the
    case or its outcome may be investigated on
    cross-examination to show bias or motive to
    falsify. A relationship between the witness and
    a party, or a financial connection such as
    employment, or hatred or dislike for a party, are
    all examples of provable bias.

Impeach a Witness by Showing a Lack of Capacity
or Impaired Capacity
  • Witness capacity consists of
  • perception,
  • memory,
  • narration,
  • sincerity.
  • Poor eyesight. poor hearing, memory, or ability
    to speak effectively are all matters that can be
    attacked in many persons.

The Law Enforcement Officeras a Witness
  • For the law enforcement officer as a witness, the
    cross-examination can become very unpleasant.
    This is probably due to the fact that the officer
    is one of the more damaging witnesses insofar as
    the defendant's case is concerned. Some defense
    attorneys may attempt to confuse, belittle, or
    embarrass an officer on the stand in the effort
    to diminish the officers testimony.

Witness Must Answer Questions
  • A witness must answer all questions the judge
    permits, whether the questions are on direct
    examination or cross-examination.

The Reluctant Witness
  • Sometimes the witness is reluctant to answer a
    question that may be adverse to the side for
    which the witness has been called, particularly
    during cross-examination.
  • To make matters worse, a witness subject to
    cross-examination may not be given a chance to
    explain his or her answer. However, the witness
    may be given the opportunity to explain the
    answer on re-direct examination.
  • The one exception to the requirement that a
    witness must answer all questions is with respect
    to a self-incriminating question.

Guarantee of the Fifth Amendment A Well-Worn
  • The Guarantee of the Fifth Amendment to the
    Constitution of the United States and the
    provisions of the constitutions of the various
    states give to a witness, in addition to the
    defendant, the right against self-incrimination.

An Unresponsive Answer
  • When an answer given to a question is not
    responsive, the unresponsive answer may be
    stricken from the record. An unresponsive answer
    is one that does not address the subject matter
    of the question that was asked or goes beyond the
    scope of the question and relates to some other

Contempt of Court or PerjuryA Dearth of Choices
  • If a witness absolutely refuses to answer a
    question and if the question is not
    incriminating, the witness can be held in
    contempt of court in addition to having his or
    her entire testimony stricken from the record.
  • Moreover, if a witness knowingly makes a false
    statement about a matter material to the case the
    witness may guilty of perjury.
  • In California, Perjury a felony.

Opinion Testimonyof Lay Witnesses
  • Opinion testimony of lay witnesses is restricted
    to those opinions or inferences that are
    "rationally based on the perception of the
    witness and . . . helpful to a clear
    understanding of the witness's testimony or the
    determination of a fact in issue."

Legally speaking, what is an opinion?
  • An opinion has been defined as an inference or
    conclusion drawn from a fact known or something
    observed. As it relates to the testimony of a
    lay witness, it would be an inference drawn from
    something the witness observed.

Guidelines on Opinion Testimony
  • The law has set guidelines by which a lay witness
    may relate information in the form of an opinion.
  • The opinion testimony must be rationally based on
    the witness's perception. In other words, the
    opinion must be one that a person could normally
    form from observed facts.

Proper Areas of Opinion Testimony
  • identity
  • handwriting
  • quantity
  • value
  • weight
  • measure
  • time
  • distance
  • velocity
  • form
  • size
  • intoxication
  • veracity

Additional Areas of Opinion Testimony We all
have some!
  • age
  • strength
  • heat
  • cold
  • sickness
  • health
  • disposition
  • temper
  • anger
  • fear
  • excitement
  • general character

Requisite Laying of a Foundation
  • Before a lay witness may express an opinion, a
    proper foundation must be laid to prove that the
    witness had personal knowledge of the facts upon
    which the opinion is formed.
  • Personal knowledge may be shown by evidence in
    the form of the witness's own testimony.
  • (A witness may not testify that something smelled
    like marijuana unless it is established that the
    witness, from prior experience, knows what
    marijuana smells like.)
  • Attention is called to the fact that the opinion
    of the lay witness may be only about something
    that the witness observed, heard, or smelled and
    not in answer to some hypothetical question
    pertaining to the witness's opinion of the matter.

Judicial Discretionin Opinion Testimony
  • A great deal of discretion has been given to the
    trial judge in determining when a witness may
    relate an opinion.

Commonly Encountered Opinions in Criminal Matters
  • State of Emotion
  • Speed of Vehicles
  • Distances
  • Sobriety or Intoxication
  • Age, Identity, and Physical Condition of a Person
  • Opinions on Miscellaneous Matters Such as Weight,
    Color, and Value
  • Character of a Person
  • Sanity (Mental Soundness)
  • Opinions About Handwriting

State of Emotion
  • It may be most important to know whether the
    accused was angry or excited at a particular
    time or whether the victim was afraid, happy, or
    in love. If the lay witness had an opportunity
    to observe the accused or the victim at the
    pertinent time, the witness may express an
    opinion of the state of emotion of each.

Speed of Vehicles
  • A lay witness who has observed a moving vehicle
    is permitted to state an opinion as to the speed
    of the vehicle. The witness need not be able to
    drive in order to state an opinion as to the
    speed, but some experience verifying that the
    witness has been able to know various speeds may
    need to be shown.

  • Opinion testimony of a lay witness is permitted
    with respect to distances between two objects, so
    long as the testimony is rationally based on the
    personal knowledge of the witness.
  • For example, a witness may give an opinion as to
    the approximate distance between an intersection
    light that turned red and a car that ran the red
    light as probative of the time the driver had to
    stop before hitting a pedestrian. If a proper
    foundation is laid showing that the witness was
    at the intersection or nearby and personally
    observed the facts testified to, then such
    testimony will be admitted

Sobriety or Intoxication
  • Often a person's sobriety or intoxication at a
    particular time is in issue, either in
    establishing guilt or mitigating a charge to a
    lesser offense. A lay witness may testify to an
    opinion that an individual was intoxicated or
    sober if it is sufficiently established that the
    witness, from prior experience, knows how an
    intoxicated or sober person appears.

Age, Identity, and Physical Condition of a Person
  • Estimated or approximate age of a person that the
    witness has observed.
  • Whether a photograph is a good likeness of the
  • Whether a voice heard over a telephone or through
    a closed door was that of someone whose voice the
    witness is able to recognize.
  • General physical characteristics of a person.
  • This includes such opinions as whether a person
    appeared to be strong, weak, feeble, or ill.
  • Generally, a lay witness may not give an opinion
    about a type of illness or any internal condition
    of a person.
  • Lay opinions should be confined to things that
    are observable.

Opinions on Miscellaneous Matters Such as Weight,
Color, and Value
  • These include an opinion about the approximate
    weight, size, and color of an object. The
    witness may state an opinion on matters of taste,
    smell, and touch. The witness may, on a limited
    basis, give an opinion of the value of certain
    objects or property. If the value is a real
    issue in the case, to arrive at it may call for
    the services of an expert.

Character of a Person
  • A witness may also testify, in the form of
    opinion, as to another witness's character for
    truthfulness or untruthfulness.
  • This is an express exception to the general rule
    prohibiting the use of character evidence for
    purposes of showing a propensity to act in a
    certain way.

Character A Powerful Opinion
  • The witness must have sufficient personal
    knowledge or experience from which an inference
    may be drawn showing another witness's character
    for telling the truth.
  • For instance, a witness may testify that he or
    she perceived the other witness telling lies and
    that in his or her opinion the other witness is
    not a truthful person. (However, the witness
    giving such an opinion may not testify about
    those specific instances of conduct. )

  • There are occasions when a lay witness may even
    express an opinion about the sanity of a person
    with whom he or she is intimately acquainted.
  • As a general rule, a lay witness may not express
    an opinion of whether the acquaintance knew the
    difference between right and wrong, as that is a
    fact that the jury is called upon to decide
    during a trial.
  • In some jurisdictions, the lay witness may not
    express an opinion as to the sanity of a person
    but may merely express an opinion as to whether
    the person in question acted in a rational or
    irrational manner.

Opinions About Handwriting
  • The common law rule, both in England and in the
    United States, often required the authenticity of
    a document or of a person's handwriting.

Lay Opinion on Handwriting
  • In earlier days, handwriting experts were
    unknown, so the services of the lay witness were
    used through necessity. It was held that if a
    witness had seen another person write or had
    received correspondence or documents from the
    person, the lay witness could express an opinion
    about the genuineness of writing.
  • Note This kind of opinion must not be confused
    with the opinions that are expressed by the
    expert witness in the field of handwriting

Expert Witnesses
  • To assist the jury in its search for the truth
    and in the best interests of justice, the
    services of the expert witness often come into

Expert Witnesses and the FRE
  • Under the FRE, an expert may testify if the
    scientific, technical, or other specialized
    knowledge he or she provides will assist the jury
    in understanding the evidence or in determining a
    material fact.

Definition of Expert Witness
  • An expert witness is a person skilled in some
    art, trade, science, or profession.
  • An expert must have either knowledge, skill,
    experience, training, or education that is beyond
    and above that of the average person.
  • In this respect, therefore, an expert is in a
    position to assist the jurors because they do not
    have this background.

Foundations andthe Expert Witness
  • Before an expert may testify, the judge must
    first determine
  • 1) Whether the witness is qualified as an expert
    in the particular field by knowledge, skill,
    experience, training, or education and,
  • 2) That the testimony will help the jury arrive
    at the truth.

The Need for Expert Witnesses
  • No matter how sophisticated a jury panel may be,
    it inevitably will be called upon to make
    judgments about many matters, some of which may
    be beyond the understanding of its members.
    Matters involving specialized knowledge are

The Benefit of an Expert Witness
  • As subject matters continue to become more
    technical and specialized, the expert witness
    will probably play an even more important role in
    trial proceedings in the future.
  • The expert witness gives the jury the benefit of
    knowledge of a particular science or skill by
    which the jurors are assisted in arriving at the

What makes an expert?
  • It is possible to become an expert witness
    through self-instruction and experience. Many of
    the crime-laboratory experts, better known as
    criminalists, fall within this category.
  • There are certain fields in which there are few
    courses available or in which there has been very
    little written.

The Foundationfor Expert Testimony
  • In order to utilize the testimony of an expert
    witness, three requirements must be established
    to the satisfaction of the trial judge.
  • First, the subject matter of the expert's
    proposed testimony must be relevant in the sense
    that it will assist the jury "to understand the
    evidence or to determine a fact in issue."
  • Second, the expert's field must be one requiring
    scientific, technical, or specialized knowledge.
  • Third, the witness must be shown to have the
    background necessary to qualify as an expert in
    the field.

Old Rule
  • Under the Frye test, only such expert testimony
    as was based on a scientific methodology
    "generally accepted as reliable in the relevant
    scientific community" was admissible.

Modern Rule
  • The Daubert test (Daubert v. Merrell Dow
    Pharmaceuticals) requires the trial judge to
    determine that the subject of an expert's
    testimony has achieved the stature of "scientific
    knowledge" based on four factors.

The Four Tests of Daubert
  • (1) testing of the theory or technique
  • (2) peer review and publication of the theory or
  • (3) the particular scientific technique's known
    or potential rate of error and
  • (4) the theory or technique's "general

The Criminalist or the Forensic Specialist
  • A Criminalist is a specialist in the application
    of physical science to crime and the law.
  • When the criminalist makes a bullet comparison or
    compares a latent fingerprint with a suspect's,
    the expert's opinion is necessary in the trial
    since the average person is unable to analyze
    such findings.

Qualifying the Expert
  • Therefore, if the criminalist has had formal
    education in ballistics and fingerprint analysis,
    this information would be elicited first by the
    prosecutor on direct examination.
  • However, even if the witness has had no formal
    education, the prosecutor can qualify the
    criminalist as an expert by eliciting information
    about the witness's special training and

Qualifying the Expert Voir Dire
  • The qualification of an expert witness places a
    burden upon the side producing the expert witness
    to prove qualification.
  • In the typical criminal case, the qualification
    process involves preliminary questions asked of
    the witness about education, experience, training
    and work in order to establish the witness's
    basic qualifications.
  • In addition, the attorney will want to qualify
    the witness as persuasively as possible by going
    beyond the essential qualifications in order to
    give the witness as much stature as possible in
    the eyes of the jury.

The Battle of the Experts
  • Persuasive qualification is particularly
    important in cases where the opposing parties
    each intend to use expert testimony with respect
    to a specific issue.

The Final ArbiterThe Judge
  • The final determination whether a person
    qualifies as an expert witness or not is made by
    the trial judge, and in most cases will not be
    overruled on appeal.
  • Once the witness is accepted by the judge as an
    expert witness, the weight given to the testimony
    is determined by the jury.

Testimony of the Expert Witness
  • The opinions and conclusions of the expert
    witness may be based upon information gained in
    one of three ways.

The First Way
  • First, specific information possessed by the
    expert, gained through examination of a
    particular piece of evidence, may be the basis of
    her opinion or conclusion.
  • (Such opinion testimony may be elicited simply by
    asking the expert what conclusions were reached
    after examining the evidence.)

The Second Way
  • Second, the expert may rely upon data supplied
    from another source in any form, as long as it is
    within the usual practice in the field to rely on
    such data. Moreover, under FRE 703, the facts
    or data upon which the expert bases an opinion
    need not be admissible at trial, provided that
    such data or facts are of a type reasonably
    relied upon by experts in the particular field.

Third Way
  • Third, the expert may be presented with a set of
    hypothetical facts from which the witness is
    asked to draw conclusions.

The Criminalist andPhysical Evidence
  • Most often, expert testimony in criminal cases
    results from an actual examination of a piece of
    physical evidence.
  • This is particularly true of testimony of
  • A criminalist's appearance as an expert witness
    originates generally from an earlier examination
    of an article found at a crime scene.

Kinds of Expert Witnesses
  • Medical Examiner or Coroner
  • Document Examiner
  • Fingerprint Expert
  • Skid-mark Expert, Speed Expert, and Accident
  • Bookmaking, Narcotics, and Other Specific Types
    of Crimes Experts

Kinds of Experts
  • Criminalist or Forensic Scientist
  • DNA Expert
  • Pattern (i.e. Footprint) Expert
  • Psychologist and Psychiatrist
  • Polygraph Examiner
  • Voiceprint Expert
  • Photographer

  • Except for certain scientific photographs, such
    as the spectrograph, micrograph, or x-ray, a
    photographer does not have to be an expert in the
    field of photography to have photographs admitted
    in evidence.

Voiceprint Expert
  • Individuals have been accepted by the courts as
    experts in the method of voice identification
    known as voiceprints.
  • This method of voice identification consists of
    identifying or eliminating an unknown voice among
    several known by both listening to the voices and
    visually inspecting a spectrogram.
  • Scientifically described, acoustical
    spectrography is a branch of science that
    consists of composing the voice or sound into
    harmonic components and obtaining a visual
    pattern of the sound. This pattern is called a

Polygraph Examiners
  • Polygraph experts allege that the polygraph is
    now beyond the experimental stage and is a
    recognized scientific instrument capable of
    detecting truthfulness and falsehood..
  • Although the courts have agreed that there has
    been substantial progress in improving the
    equipment and the operator techniques used in
    administering polygraph tests, very few courts
    will allow evidence of polygraph results to be
    admitted for any purpose.

Psychologists and Psychiatrists
  • It is recognized that doctors specializing in
    psychiatry or psychology may state their opinion
    on the sanity of a person, but a perplexing
    problem arises as to whether a psychologist or
    psychiatrist may state an opinion on the sanity
  • It is known that sanity is a matter of mental
    illness, thus a psychologist or psychiatrist who
    is trained and experienced in mental illnesses
    may qualify as an expert on mental illness and
    express an opinion on the sanity of a person.

Footprint Experts
  • Footprints are admitted in evidence when their
    similarity to the shoes worn by a defendant
    justifies an inference that the prints were made
    by his or her shoes.
  • Often there is not much that science can add to a
    comparison of a cast or photograph made of a
    footprint found at a crime scene with the shoe of
    a suspect.
  • Thus, similarities in any peculiar markings
    between the cast or photograph and the shoe, as
    well as a comparison of the size, may often be
    made by the jury with as much proficiency as an
    expert witness.

DNA Experts
  • The area of DNA evidence requires the assistance
    of highly-educated and trained experts.
  • Use of DNA evidence requires scientific
    knowledge, and therefore it would be impossible
    for an officer or a person, by way of training or
    experience only, to give an opinion with respect
    to such evidence.
  • It is necessary to have experts educated in the
    fields of genetics, biology, chemistry and other
    sciences to testify as DNA experts concerning
    such evidence. Usually scientists, those with
    advanced degrees in the sciences, will be
    required to testify, as this lends more
    credibility to their testimony in the eyes of the

Criminalist or Forensic Scientist
  • A few of the more commonly encountered ones are
    in the fields of
  • ballistics,
  • spectroscopic examinations,
  • the examination of hairs and fibers, soils,
  • toxicology,
  • glass and glass fractures,
  • blood and other body fluids,
  • paints, and chemicals.

Bookmaking Experts
  • Officers who have had extensive experience in
    working on particular types of crimes may become
    qualified as crimes experts with respect to those
    particular crimes. For example, officers who
    work on bookmaking cases may become qualified as
    experts in what is considered to be material and
    paraphernalia used by bookmakers.

Narcotics and Other Specific Types of Crimes
  • Officers experienced in drug investigations may
    qualify to testify on drug users' methods of
    taking drugs.
  • They may also express their opinion about scars
    that they believe to have been made by injections
    or whether certain paraphernalia found at a crime
    scene were used by those engaged in the use or
    sale of narcotics.
  • The narcotic content of a pill or powder,
    however, would have to be determined by a person
    skilled in the field of chemistry.

Skid-Mark Expert, Speed Expert, and Accident
  • Serious motor vehicle accidents are a fact of
    life in all societies. In many instances, there
    are few, if any, eyewitnesses to automobile
    accidents, so that determination of the speed of
    the vehicles involved in accidents is not easily
    made, yet the speed is often an important factor
    of a case.

Fingerprint Expert
  • The services of the fingerprint expert come into
    the picture when it is necessary to make a
    comparison between a latent fingerprint at a
    crime scene and the prints of a known suspect to
    determine whether the latent print is that of the
  • If an identification is made, the examiner will
    in most instances be called as a witness to prove
    the basis upon which an identification was made.

Medical Examiner or Coroner
  • In homicide cases, the cause of death must be
    established. This is invariably done by the
    medical examiner or coroner.
  • The examiner will be called as an expert witness
    by the prosecution to give an opinion of the
    cause of death as a result of an examination of
    the body.
  • It is only after the coroner or medical examiner
    has made a complete examination of the body that
    he or she can conclude that the death was due to
    stabbing and not to a heart attack, or that a
    death was due to strangulation and not to
    accidental drowning.

Document Examiner
  • A document examiner is usually skilled in making
    comparisons of handwritten documents and
    documents produced by all other means. Such a
    person would be able to qualify as a handwriting
    expert and an expert in the field of document
    examination generally.

The Handwriting Expert
  • The handwriting expert is seldom acquainted with
    the person whose writing he or she examines.
    Instead, the expert's examination is purely a
    comparison of two or more writings.
  • The expert may compare two checks in an effort to
    determine whether they were written by the same
  • Or the expert may have a sample of the known
    handwriting of a person to compare to a
    questioned check or document in an effort to form
    an opinion whether the questioned document was
    written by the person who gave the known
    handwriting sample.
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