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Chapter 18Chapter 18

Scientific EvidenceScientific Evidence

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The use of scientific The use of scientific evidenceevidence

Even though scientific evidence is not Even though scientific evidence is not infallible, it could contribute to an infallible, it could contribute to an investigation by:investigation by:

Providing a lead or leads to head a Providing a lead or leads to head a criminal investigation in the right criminal investigation in the right direction.direction.

Providing information eliminating a Providing information eliminating a suspect as the person who committed suspect as the person who committed the crime being investigated.the crime being investigated.

Proving corpus delicti, or proof that a Proving corpus delicti, or proof that a crime was committed .crime was committed .

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Providing the independent Providing the independent corroborative evidence necessary corroborative evidence necessary to support a confession to support a confession

Establishing a link between the Establishing a link between the crime scene and the suspect or crime scene and the suspect or between the suspect and the between the suspect and the victim of the crime.victim of the crime.

Proving one of the essential Proving one of the essential elements of the crime being elements of the crime being investigated.investigated.

Affirming or disproving an alibi.Affirming or disproving an alibi.

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Establishing the innocence of people Establishing the innocence of people not involved in the crime.not involved in the crime.

Encouraging or inducing a person to Encouraging or inducing a person to make a confession or an incriminating make a confession or an incriminating admission when the person is admission when the person is confronted with scientific evidence that confronted with scientific evidence that incriminates them.incriminates them.

Providing reasonable suspicion or Providing reasonable suspicion or probable cause.probable cause.

Building such strong cases against Building such strong cases against defendants that the number of guilty defendants that the number of guilty pleas are increased, clearing court pleas are increased, clearing court calendars and permitting faster trials of calendars and permitting faster trials of contested cases.contested cases.

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What is scientific evidence?What is scientific evidence?

Scientific evidence is most often Scientific evidence is most often presented in court by an expert witness presented in court by an expert witness testifying as to expert opinions. It also testifying as to expert opinions. It also includes expert testimony that goes includes expert testimony that goes beyond science. The scientific expert is beyond 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.

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Courts traditionally use one of Courts traditionally use one of these rules for the admissibility of these rules for the admissibility of

scientific evidence.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-The Frye Test Plus or KELLY-

Frye testFrye test People v. KellyPeople v. Kelly (1976) 17 Cal.3d 24 (1976) 17 Cal.3d 24 Daubert TestDaubert Test Daubert v. Merrell-Dow Daubert v. Merrell-Dow

Pharmaceuticals, IncPharmaceuticals, Inc. 509 U.S. 579, 113 . 509 U.S. 579, 113 S.Ct. 2786 (1993).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 Essentially, for the results of a

scientific technique to be scientific technique to be admissible, the technique must admissible, the technique must be sufficiently established to be sufficiently established to have gained general acceptance have gained general acceptance in its particular field. in its particular field.

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

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Kelly-Frye HearingsKelly-Frye Hearings

Kelly-Frye hearings are preliminary hearings Kelly-Frye hearings are preliminary hearings in which the judge determines whether or in which the judge determines whether or not to permit particular scientific evidence not to permit particular scientific evidence to be presented to the jury during trial. to be presented to the jury during trial.

In a typical Kelly-Frye hearing, both the In a typical Kelly-Frye hearing, both the proponent and the opponent of the proponent and the opponent of the scientific technique bring in a parade of scientific technique bring in a parade of scientific experts and present their best scientific experts and present their best arguments for or against the admissibility arguments for or against the admissibility of the particular scientific evidence involvedof the particular scientific evidence involved

California uses the Kelly-Frye TestCalifornia uses the Kelly-Frye Test

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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 testedHas the theory been tested Has it been subjected to peer review by Has it been subjected to peer review by

other scientistsother scientists What is the theory’s or technique’s known What is the theory’s or technique’s known

or potential rate of erroror potential rate of error Do standards controlling the application of Do standards controlling the application of

the theory or techniquethe theory or technique Is the theory or technique generally Is the theory or technique generally

acceptedaccepted

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

basic “FRYE” test of "general basic “FRYE” test of "general acceptance" in the scientific acceptance" in the scientific communitycommunity

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 hearings for scientific evidence and special procedures on and special procedures on discovery.  discovery. 

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

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Daubert test requires (Federal) Daubert test requires (Federal) Judges to ascertain the following: Judges to 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 (3) the known or potential rate of error in using a particular scientific technique in using a particular scientific technique and the standards controlling the and the standards controlling the technique's operation; and technique's 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.

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Frye v. Daubert? Frye v. Daubert? In terms of DNA admissibility, the two major In terms of DNA admissibility, the two major

differences between Frye and Daubert are:differences between Frye and Daubert are: (1) Daubert requires a consideration of (1) Daubert requires a consideration of

error rates whereas Frye typically does error rates whereas Frye typically does not; not;

(2) in Frye jurisdictions, the debate (2) in Frye jurisdictions, the debate over how to calculate the significance over how to calculate the significance of a genetic match goes toward the of a genetic match goes toward the admissibility of the evidence, whereas admissibility of the evidence, whereas in Daubert jurisdictions, it goes toward in Daubert jurisdictions, it goes toward the weight the weight

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Judicial Role in DaubertJudicial Role in Daubert

The essence of Daubert is that The essence of Daubert is that the Supreme Court has deputized the Supreme Court has deputized federal district judges as federal district judges as "gatekeepers," authorizing them "gatekeepers," authorizing them to exercise broad discretion to to exercise broad discretion to exclude whatever evidence they exclude whatever evidence they deem not to meet scientific deem not to meet scientific standards of admissibility standards of admissibility

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StateState v v FederalFederal

States can “choose” States can “choose” between the tests and between the tests and decide on which is “their” decide on which is “their” standardstandard

The Federal Courts must The Federal Courts must use Daubertuse Daubert

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DNA Genetic ProfilingDNA Genetic Profiling

Deoxyribonucleic acid (DNA) testing has Deoxyribonucleic acid (DNA) testing has become an important become an important forensic forensic tool for tool for linking suspects to a crime.linking suspects to a crime.

Equally importantly, DNA testing has made Equally importantly, DNA testing has made it possible to eliminate a suspect in a crime, it possible to eliminate a suspect in a crime, sometimes even after the suspect has been sometimes even after the suspect has been convicted of that crime. (Exculpatory convicted of that crime. (Exculpatory Evidence)Evidence)

DNA genetic profilingDNA genetic profiling has received such has received such wide acceptance among criminal justice wide acceptance among criminal justice professionals that it is frequently called professionals that it is frequently called genetic fingerprinting.genetic fingerprinting.

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DNA Genetic Profiling cont….DNA Genetic Profiling cont….

Locus pointsLocus points:: base pairs that vary from one base pairs that vary from one individual to the next can be located. individual to the next can be located.

For example, where eye color is determined, For example, where eye color is determined, base pairs will join in a sequence that is base pairs will join in a sequence that is repeatedrepeated

Measuring the size of a repetitive sequence of Measuring the size of a repetitive sequence of base pairs at many such locations gives a base pairs at many such locations gives a fingerprint-like picture of the DNA chain since fingerprint-like picture of the DNA chain since at these locations the sequence of base pairs at these locations the sequence of base pairs varies among different individualsvaries among different individuals

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The FBI Laboratory's Combined DNA Index The FBI Laboratory's Combined DNA Index System (CODIS) blends forensic science System (CODIS) blends forensic science and computer technology into an effective and computer technology into an effective tool for solving violent crimes. CODIS tool for solving violent crimes. CODIS enables state and local crime laboratories enables state and local crime laboratories to exchange and compare DNA profiles to exchange and compare DNA profiles electronically, thereby linking serial electronically, thereby linking serial violent crimes to each other and to known violent crimes to each other and to known sex offenders. (A DNA profile is the set of sex offenders. (A DNA profile is the set of genetic characteristics that result from genetic characteristics that result from forensic DNA analysis.) forensic DNA analysis.) http://www.fbi.gov/hq/lab/codis/index1.htmhttp://www.fbi.gov/hq/lab/codis/index1.htm

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FBI’s Report on What Police FBI’s Report on What Police Officers Need to Know about Officers Need to Know about

DNADNA http://www.ncjrs.org/pdffiles1/jr0002http://www.ncjrs.org/pdffiles1/jr0002

49c.pdf49c.pdf Excellent resource for the Criminal Excellent resource for the Criminal

Justice Student or Police OfficerJustice Student or Police Officer

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Forensic EntomologyForensic Entomology

EntomologyEntomology is the study of insects. is the study of insects. Forensic Entomology is used to determine the Forensic Entomology is used to determine the

time since death on human cadavers and also time since death on human cadavers and also other facts surrounding the death such as other facts surrounding the death such as location, placement, movement of the body and location, placement, movement of the body and information on the manner of death.information on the manner of death.

Board of Forensic Entomology: Board of Forensic Entomology: http://www.missouri.edu/~agwww/entomology/http://www.missouri.edu/~agwww/entomology/ International Forensic Entomology links: International Forensic Entomology links: http://http://

folk.uio.no/mostarke/forens_ent/forensic_entomologfolk.uio.no/mostarke/forens_ent/forensic_entomology.htmly.html

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Forensic OdontologyForensic Odontology American Board of Forensic OdontologyAmerican Board of Forensic Odontology http://www.abfo.org/http://www.abfo.org/ The objective of the Board is to establish, The objective of the Board is to establish,

enhance, and revise as necessary, standards enhance, and revise as necessary, standards of qualifications for those who practice of qualifications for those who practice forensic odontology, and to certify as qualified forensic odontology, and to certify as qualified specialists those voluntary applicants who specialists those voluntary applicants who comply with the requirements of the Board. comply with the requirements of the Board.

In this way, the Board aims to make available In this way, the Board aims to make available a practical and equitable system for a practical and equitable system for readily readily identifying those persons professing to be identifying those persons professing to be specialists in forensic odontologyspecialists in forensic odontology who possess who possess the requisite qualifications and competence the requisite qualifications and competence

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The International Association for The International Association for IdentificationIdentification

http://www.theiai.org/http://www.theiai.org/ IAI has grown into the most prestigious IAI has grown into the most prestigious

professional association of its kind in the professional association of its kind in the world, with more than 5,000 members from world, with more than 5,000 members from the United States and many other countries. the United States and many other countries. The advancement of forensic disciplines The advancement of forensic disciplines through education continues to be one of the through education continues to be one of the top priorities of the Association. top priorities of the Association.

THE IAI also “CERTIFIES” forensic experts in THE IAI also “CERTIFIES” forensic experts in a variety of areas of expertise in Forensics. a variety of areas of expertise in Forensics.

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American Academy of Forensic American Academy of Forensic ScienceScience

http://www.aafs.org/http://www.aafs.org/ As a professional society dedicated As a professional society dedicated

to the application of science to the to the application of science to the law, the AAFS is committed to the law, the AAFS is committed to the promotion of education and the promotion of education and the elevation of accuracy, precision, and elevation of accuracy, precision, and specificity in the forensic sciences specificity in the forensic sciences

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Ballistics Fingerprinting or firearm Ballistics Fingerprinting or firearm fingerprintingfingerprinting

The rifling of the barrel of the gun The rifling of the barrel of the gun leaves unique marks in the lead or leaves unique marks in the lead or steel of the bullet fragment. steel of the bullet fragment.

This technology is often called This technology is often called ballistic fingerprinting ballistic fingerprinting

Technicians can then enter a digital image of Technicians can then enter a digital image of the tiny markings into a computer data base the tiny markings into a computer data base called the called the National Integrated Ballistic National Integrated Ballistic Information Network.Information Network. The computer then The computer then spits out likely matches which the examiners spits out likely matches which the examiners can then study further under a microscope.can then study further under a microscope.

NIBIN on the web: NIBIN on the web: http://www.nibin.gov/http://www.nibin.gov/

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Sources of other scientific Sources of other scientific evidenceevidence

Other scientific evidence used regularly in courts Other scientific evidence used regularly in courts throughout the united states include:throughout the united states include:

Test for alcoholic intoxication Test for alcoholic intoxication Fire and explosive science evidenceFire and explosive science evidence Forensic pathologyForensic pathology Chemistry, toxicology, serology Chemistry, toxicology, serology Microanalysis Microanalysis Neutron activation analysis (NAA)Neutron activation analysis (NAA) Tests used in questioned documentsTests used in questioned documents Scientific detection of speedingScientific detection of speeding Accident Reconstruction Accident Reconstruction Forensic odontologyForensic odontology Accident reconstruction techniquesAccident reconstruction techniques Physical anthropology Physical anthropology