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What Is Scientific Evidence?What Is Scientific Evidence?

Scientific evidence is most often presented Scientific evidence is most often presented in court by an expert witness testifying in court by an expert witness testifying on expert opinions. It also includes on expert opinions. It also includes expert testimony that goes beyond expert testimony that goes beyond science. The scientific expert is science. The scientific expert is frequently called upon to interpret frequently called upon to interpret results and draw conclusions about results and draw conclusions about what results mean in the case being what results mean in the case being tried.tried.

Functions of the Forensic Functions of the Forensic ScientistScientist

Forensic Scientists rely primarily Forensic Scientists rely primarily on scientific knowledge. However, on scientific knowledge. However, only half the job is performed in the only half the job is performed in the laboratory while the other half laboratory while the other half takes place in the courtroom.takes place in the courtroom.

These functions fit into three These functions fit into three categories:categories:

PHYSICAL EVIDENCE IS LESS LIKELY TO BE PHYSICAL EVIDENCE IS LESS LIKELY TO BE COMPROMISED OR TAINTED BY HUMAN EMOTIONS COMPROMISED OR TAINTED BY HUMAN EMOTIONS THAN EYEWITNESS ACCOUNTS FROM VICTIMS OR THAN EYEWITNESS ACCOUNTS FROM VICTIMS OR WITNESSES ORWITNESSES OR COERCED CONFESSIONSCOERCED CONFESSIONS

THE ANALYSIS OF PHYSICAL EVIDENCE INVOLVES THE ANALYSIS OF PHYSICAL EVIDENCE INVOLVES ADHERENCE TO STRICT GUIDELINES, SYSTEMATIC ADHERENCE TO STRICT GUIDELINES, SYSTEMATIC COLLECTION, ORGANIZATION AND ANALYSIS OF COLLECTION, ORGANIZATION AND ANALYSIS OF INFORMATION (THE SCIENTIFIC METHOD)INFORMATION (THE SCIENTIFIC METHOD)

AN UNDERSTANDING OF THE ADMISSIBILITY OF AN UNDERSTANDING OF THE ADMISSIBILITY OF EVIDENCE IS IMPORTANT.EVIDENCE IS IMPORTANT.

2. Providing Expert 2. Providing Expert TestimonyTestimony Forensic Scientist are called on to evaluate Forensic Scientist are called on to evaluate

evidence when the court lacks the expertise to do soevidence when the court lacks the expertise to do so

Must establish competency by citing educational Must establish competency by citing educational degrees, number of years of occupational degrees, number of years of occupational experience membership in professional societies, experience membership in professional societies, special courses taken and any professional articles special courses taken and any professional articles or books published.or books published.

Cross-examination may reveal weaknesses in Cross-examination may reveal weaknesses in background and knowledgebackground and knowledge

Demeanor and ability to explain scientific data Demeanor and ability to explain scientific data clearly and logically to a judge and jury of non-clearly and logically to a judge and jury of non-scientistsscientists

Must be an advocate of truth and not take a sideMust be an advocate of truth and not take a side

3. Providing Training 3. Providing Training Evidence must be properly recognized, collected Evidence must be properly recognized, collected

and preserved if it is to have value.and preserved if it is to have value. Many, but not all crime laboratories keep trained Many, but not all crime laboratories keep trained

““evidence techniciansevidence technicians””.. Sometimes a patrol officer or detective collects Sometimes a patrol officer or detective collects

the evidence.the evidence. All officers engaged in fieldwork must be familiar All officers engaged in fieldwork must be familiar

with evidence collection.with evidence collection. These people are trained by laboratory staff These people are trained by laboratory staff

through extensive personal contact, lectures, through extensive personal contact, lectures, laboratory tours and/or dissemination of laboratory tours and/or dissemination of manuals.manuals.

Admissibility of Scientific Admissibility of Scientific EvidenceEvidence

How does the court decide whether or How does the court decide whether or not to accept scientific evidence? The not to accept scientific evidence? The judge and jury are typically not judge and jury are typically not scientifically trained.scientifically trained.

Several court cases illustrate the Several court cases illustrate the steps in the development of steps in the development of admissibility.admissibility.

Frye vs. United States Frye vs. United States (1923)(1923)

Scientific validity of polygraph is rejectedScientific validity of polygraph is rejected Court ruled that in order to be admitted as Court ruled that in order to be admitted as

evidence in trial the questioned procedure, evidence in trial the questioned procedure, technique or procedure must be technique or procedure must be ““generally generally acceptedaccepted”” by a meaningful segment of the by a meaningful segment of the scientific community.scientific community.

Collection of experts called in to testify Collection of experts called in to testify about the validity of scientific issuesabout the validity of scientific issues

Books and papers written on subject Books and papers written on subject reviewed and discussed.reviewed and discussed.

Federal Rules of Federal Rules of Evidence (1975):Evidence (1975):

A code of evidence law governing the A code of evidence law governing the admissibility of evidence in the U.S. federal admissibility of evidence in the U.S. federal court system enacted in 1975.court system enacted in 1975.

Rule 702 applies to scientific, technical or Rule 702 applies to scientific, technical or otherwise specialized knowledge.otherwise specialized knowledge.

Individual states are free to adopt different Individual states are free to adopt different evidence rules but most have codes that evidence rules but most have codes that are based on FRYE.are based on FRYE.

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Courts traditionally use one of these rules Courts traditionally use one of these rules for the admissibility of scientific evidence:for the admissibility of scientific evidence:

The Frye TestThe Frye Test Frye v. United StatesFrye v. United States (1928) 293 F. 1013 (1928) 293 F. 1013

The Frye Test Plus or KELLY-Frye The Frye Test Plus or KELLY-Frye testtest People v. KellyPeople v. Kelly (1976) 17 Cal.3d 24 (1976) 17 Cal.3d 24

Daubert TestDaubert Test Daubert v. Merrell-Dow Pharmaceuticals, IncDaubert v. Merrell-Dow Pharmaceuticals, Inc. 509 . 509

U.S. 579, 113 S.Ct. 2786 (1993).U.S. 579, 113 S.Ct. 2786 (1993).

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Frye Standard, Frye Standard, Frye v. U.S. Frye v. U.S. 293 F. 1013 (D.C. Cir. 1923)293 F. 1013 (D.C. Cir. 1923)

Essentially, for the results of a scientific Essentially, for the results of a scientific technique to be admissible, the technique to be admissible, the technique must be sufficiently technique must be sufficiently established to have gained general established to have gained general acceptance in its particular field. acceptance in its particular field.

This is referred to as the "general This is referred to as the "general acceptance" test by the scientific acceptance" test by the scientific community. community.

Illinois Rules of Evidence Rule 702 TESTIMONY BY EXPERTS

If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.

Where an expert witness testifies to an opinion based on a new or novel scientific methodology or principle, the proponent of the opinion has the burden of showing the methodology or scientific principle on which the opinion is based is sufficiently established to have gained general acceptance in the particular field in which it belongs.

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Although there had been considerable clamoring for Illinois to adopt the Daubert test, as the Federal courts and many other jurisdictions have done, the Illinois Supreme Court has made it clear that it is Frye and not Daubert that must be followed.

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the testimony is based upon sufficient facts or data, the testimony is the product of reliable principles and methods, and the witness has applied the principles and methods reliably to the facts of the case.

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The Frye test as set forth in Frye v. United States, 293 F. 1013 (D.C. Cir. 1923), is a specific test of admissibility related to expert testimony concerning scientific evidence. Where opinion testimony is based on the expert’s personal knowledge and practical experience, but not based on “studies and tests,” it is not subject to a Frye test. Donnellan v. First Student, Inc., 383 Ill. App. 3d 1040, 1061, 891 N.E.2d 463 (1st Dist. 2008). The Frye test is also known as the “general acceptance” test, as it requires that “the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.

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The Daubert TestThe Daubert Test The court suggested the trial court consider The court suggested the trial court consider

various factors to assess scientific validityvarious factors to assess scientific validity Has the theory been tested?Has the theory been tested? Has it been subjected to peer review by other Has it been subjected to peer review by other

scientists?scientists? What is the theoryWhat is the theory’’s or techniques or technique’’s known or s known or

potential rate of error?potential rate of error? Do standards controlling the application of the Do standards controlling the application of the

theory or technique?theory or technique? Is the theory or technique generally accepted?Is the theory or technique generally accepted?

Daubert v. Dow Pharmaceuticals, Inc. Daubert v. Dow Pharmaceuticals, Inc. (1993)(1993)

““general acceptancegeneral acceptance”” or Frye standard or Frye standard no longer absolute prerequisite.no longer absolute prerequisite.

Trial judge given the task of ensuring Trial judge given the task of ensuring an expert testimony rests on a reliable an expert testimony rests on a reliable foundation, is relevant to case, and is foundation, is relevant to case, and is not repetitive, inflammatory or not repetitive, inflammatory or unnecessarily confusing. (gatekeeper)unnecessarily confusing. (gatekeeper)

Daubert Ruling Daubert Ruling suggested areas of suggested areas of inquiry:inquiry:

Whether the scientific technique or theory Whether the scientific technique or theory can be (and has been) tested.can be (and has been) tested.

Whether the technique or theory has been Whether the technique or theory has been subject to peer review & publicationsubject to peer review & publication

The techniqueThe technique’’s potential rate of errors potential rate of error The existence and maintenance of The existence and maintenance of

standardsstandards Whether the scientific theory or method has Whether the scientific theory or method has

attracted widespread acceptance within a attracted widespread acceptance within a relevant scientific communityrelevant scientific community

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Daubert v. Merrell Dow Daubert v. Merrell Dow (1993) (1993) The Court The Court ““REJECTEDREJECTED”” the more basic the more basic

Frye test of Frye test of ““general acceptancegeneral acceptance”” in the in the scientific community.scientific community.

Daubert requires an independent Daubert requires an independent judicial assessment of reliability .judicial assessment of reliability .

This test requires special pretrial This test requires special pretrial hearings for scientific evidence and hearings for scientific evidence and special procedures on discovery.  special procedures on discovery. 

This is a more stringent test that This is a more stringent test that requires knowledge of Type I and Type II requires knowledge of Type I and Type II error rates, as well as validity and error rates, as well as validity and reliability coefficientsreliability coefficients..

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Daubert test requires (federal) judges to Daubert test requires (federal) judges to ascertain the following: ascertain the following:

(1) Whether the theory or technique is (1) Whether the theory or technique is capable of being or has been tested;capable of being or has been tested;

(2) Whether it has been subjected to peer (2) Whether it has been subjected to peer review and publication;review and publication;

(3) The known or potential rate of error in (3) The known or potential rate of error in using a particular scientific technique and using a particular scientific technique and the standards controlling the technique's the standards controlling the technique's operation; and operation; and

(4) Whether the theory or technique is (4) Whether the theory or technique is generally accepted in the particular generally accepted in the particular scientific field. scientific field.

Concerns about the Daubert Concerns about the Daubert Ruling:Ruling:

Abandoning FryeAbandoning Frye’’s general acceptance test s general acceptance test will result in the introduction of absurd will result in the introduction of absurd pseudoscientific claims in courtpseudoscientific claims in court

Supreme Court rejected these concerns:Supreme Court rejected these concerns: The judicial system is capableThe judicial system is capable Through vigorous cross-examination, Through vigorous cross-examination,

presentation of contrary evidence and careful presentation of contrary evidence and careful instruction on the burden of proof are the instruction on the burden of proof are the traditional & appropriate means of attacking traditional & appropriate means of attacking shaky but admissible evidence.shaky but admissible evidence.

Different methods-same results: Different methods-same results: ““Frye in dragFrye in drag””