See also: BLOOD; GENETIC TESTING
HUMAN LEUKOCYTE ANTIGEN TEST ; PATERNITY

1.  Generally

This article addresses the admissibility of evidence based on deoxyribonucleic acid (DNA) testing.  DNA testing compares characteristics of DNA samples in order  to identify persons or determine whether there is a relationship between them.  When performed properly, it is extremely accurate.{footnote}Colorado v. Fishback, 829 P.2d 489 (Colo. Ct. App. 1991), aff’d, 851 P.2d 884, 892 (1993); Andrews v. State, 533 So.2d 841, 890 (Fla. App. 1988), aff’d, 542 So.2d 1332 (1989); Missouri v. Davis, 814 S.W.2d 593 (Mo. 1991).{/footnote}   DNA testing is one of several forms of genetic testing.  Other forms of genetic testing examine what are known as secondary genetic characteristics, such as antigens, blood proteins, and enzymes. 

Testimony as to DNA evidence falls into two distinct phases.  First, there must be testimony as to the laboratory testing performed and the observations made.  Second, the proponent generally offers a statistical analysis of the test results.  Each of these two phases of the proponent’s DNA testimony must be shown to pass scrutiny as reliable scientific evidence.{footnote}People v. Barney, 10 Cal. Rptr. 2d 731 (Cal. Ct. App. 1992); Murray v. Florida, No. 83-556 (Fla. Supr. 4/17/97); People v. Watson, 629 N.E.2d 634 (Ill. App. Ct. 1994).{/footnote}

2.  The Nature of DNA Testing

The DNA molecule is found in every cell which contains a nucleus.  Thus, DNA may be extracted from several possible sources, including blood, semen and tissue.  Usable specimens may be taken from a fetus, a newborn or even a cadaver, provided the cadaver is not severely decomposed.{footnote}Pace v. State, 648 So. 2d 1302, 1302 (La. 1995); In re Estate of Rogers, 583 A.2d 782 (N.J. Super. Ct. App. Div. 1990).
CHECK Sudwischer v. Estate of Hoffpauir, 589 So.2d 474 (La. 1991).
Charles N. LeRay, Implications of DNA Technology on Posthumous Paternity Determination: Deciding the Facts When Daddy Can’t Give His Opinion, 35 B.C. L. Rev. 747 (1994).{/footnote}  Chemicals and centrifugal force are used to separate out the DNA from the sample.

DNA is made up of four chemical bases strung together in pairs in extremely long sequences.  Enzymes called restriction endonucleases are used to break down a cell’s DNA into fragments at specific locations.   Some of these fragments have become known as restriction fragment length polymorphisms (RFLPs) due to their variability.

All of the DNA fragments are injected into a gel and separated into bands through the use of electrophoresis.  An electrical current is applied to one side of the gel, causing the fragments to migrate to the opposite side. The smaller fragments travel faster than the larger fragments.  The current is then removed and the fragments are single-stranded (or "unzipped").

The single-stranded band pattern is transferred to a nylon membrane.{footnote}David B. Jackson, DNA Fingerprinting and Proof of Paternity, 15 The Family Law Reporter 3007 (May 16, 1989).{/footnote}  The membrane is placed in a dish containing radioactive "probes."  These "probes" are actually DNA fragments created in a laboratory through cloning.  They consist of known base pair sequences which have been tagged with a radioactive isotope.  These probes, after being single-stranded, will attach to a complementary base pair sequences of the sample DNA.  The dish is left overnight, excess probes are washed off, and the membrane is placed on X-ray film.  The film and the membrane are frozen for 72 hours, after which time the membrane is removed and stored in plastic wrap. 

The X-ray film is then studied for the identifying dark bands.  The dark bands show where the radioactive probes attached to the sample DNA fragments.

The FBI pioneered a method of DNA analysis known as "fixed bin analysis" which has been widely used, and accepted by courts.{footnote}People v. Watson, 629 N.E.2d 634 (Ill. App. Ct. 1994).{/footnote}

Two types of tests{footnote}Annot., Admissibility of DNA Identification Evidence, 84 A.L.R.4th 313 § 4 at 335-341(1991).{/footnote}

2(a).  Polymerase Chain Reaction (PCR) Testing.

Polymerase Chain Reaction (PCR) test results have been held inadmissible where the expert witness failed to explain the procedure involved, and erroneously claimed that PCR testing had been endorsed by the National Research Council.{footnote}Murray v. Florida, No. 83-556 (Fla. Supr. 4/17/97).{/footnote}

3.  Statistical Evidence

To say that two samples "match" is essentially meaningless, because it does not convey to the trier of fact the likelihood or unlikelihood of such a match with a random sample.{footnote}Murray v. Florida, No. 83-556 (Fla. Supr. 4/17/97); State v. Carter, 246 Neb. 953, 524 N.W.2d 763, 783 (1994).
National Research Council, DNA Technology in Forensic Science 74 (1992).{/footnote}  To be meaningful, the test results must be described in statistical terms:

To help a court or jury to understand the importance of a match, most experts provide quantitative, rather than qualitative, estimates of the frequency of an incriminating profile in one or more races or an upper bound on the frequency.{footnote}Committee on DNA Forensic Science & Commission on DNA Forensic Science, National Academy of Sciences, The Evaluation of Forensic DNA Evidence at 6‑ 24‑ ‑ 6‑ 26 (1996).{/footnote}

Thus, the proponent of DNA evidence will generally offer statistical evidence in an attempt to underscore quantitatively the import of the "match."

Unlike many of the technical aspects of DNA typing that are validated by daily use in hundreds of laboratories, the extraordinary population‑ frequency estimates sometimes reported for DNA typing do not arise in research or medical applications that would provide useful validation of the frequency of any particular person’s DNA profile.  Because it is impossible or impractical to draw a large enough population to test calculated frequencies for any particular DNA profile much below 1 in 1,000, there is not a sufficient body of empirical data on which to base a claim that such frequency calculations are reliable or valid per se.{footnote}National Research Council, DNA Technology in Forensic Science 77 (1992), quoted in Murray v. Florida, No. 83-556 (Fla. Supr. 4/17/97).{/footnote}

The prosecution generally offers statistical evidence demonstrating that the defendant’s DNA and DNA found at the crime scene share a rare combination of genetic markers.  To establish how rare the combination is, a prosecution expert identifies specific genetic markers found in each DNA sample.  The expert then determines the frequency with which each marker occurs in the population based upon studies of the relevant population. The expert then uses the "product rule" to multiply the frequencies of each separate genetic marker.{footnote}One court illustrated the product rule as follows:
            If one had to choose an automobile numbered but not seen and there were 5 hardtops and 5 convertibles, the probability of selecting a convertible would be 1 out of 2. If 5 of the automobiles are blue, the probability of selecting a blue automobile is 1 out of 2, and the probability of selecting a blue convertible is 1 out of 4. If only convertibles are colored blue, the probability of selecting a blue convertible reverts back to 1 out of 2.
People v. Wesley, 533 N.Y.S.2d 643, 657 n.23 (N.Y. Co. Ct. 1988); John McCabe, DNA Fingerprinting: The Failings of Frye, 16 N.Ill.U. L.Rev. 455, 463 n. 41 (1996).{/footnote}  The result the frequency with which the combination of genetic markers occurs in the population.

The defense may attack an assumption on which this statistical method is based: that the genetic markers at issue are  distributed randomly in the population used by the FBI (e.g., Caucasions, blacks, Hispanics).  Defense experts sometimes suggest that subgroups may exist within, say, the Caucasion population, based on ethnicity{footnote}See Commonwealth v. Curnin, 565 N.E.2d 440, 445 (Mass. 1991).{/footnote} or geography.{footnote}See Commonwealth v. Curnin, 565 N.E.2d 440, 445 (Mass. 1991).{/footnote}  This theory, known as substructuring, was decribed by Professor Richard Lewontin and Dr. Daniel Hartl,{footnote}Richard C. Lewontin & Daniel L. Hartl, Population Genetics in Forensic
DNA Typing, 254 Science 1745 (1991).{/footnote} and challenged by Professors Ranajit Chakraborty and Kennth Kidd.  Professors Chakraborty and Kidd analyzed the same data as Professor Lewontin and Dr. Hartl, but determined that  even if substructuring occurs, it does not affect the reliability of the probability calculations performed by the FBI.{footnote}Ranajit Chakraborty & Kenneth K. Kidd, The Utility of DNA Typing in
Forensic Work, 254 Science 1735 (1991).
See also Bernard Devlin et al., Statistical Evaluation of DNA Fingerprinting:
A Critique of the NRC’s Report, 259 Science 748 (1993) (contending that the reliability of DNA statistical evidence is well-established).{/footnote}   The FBI itself has answered the substructuring theory with an extensive five-volume study of VNTR data.{footnote}[CITE?]{/footnote}

In an effort to resolve the dispute over the reliability of DNA forensic evidence, the National Research Council (NRC) convened a committee to study the issue, and published its report in 1992.{footnote}National Research Council, DNA Technology in Forensic Science (1992) (the "NRC Report").{/footnote}  The NRC report acknowledged the controversy in the scientific community over the reliability of DNA statistical evidence and recommended specific improvements in the methods used, including the creation of standardized laboratory procedures, proficiency testing and laboratory accreditation.  The report also recommended that laboratory error rates be disclosed to the jury.  {footnote}NRC Report at 88-89.{/footnote}The report ultimately concluded that DNA statistical evidence should be admissible as evidence whether or not the NRC’s suggestions have been followed:

We recommend that the use of DNA analysis for forensic purposes, including the resolution of both criminal and civil cases, be continued while improvements and changes suggested in this report are being made. There is no need for a general moratorium on the use of the results of DNA typing either in investigation or in the courts.{footnote}NRC Report at [131‑151?].
But see Peter Aldhous, Geneticists Attack NRC Report as Scientifically Flawed, 259 Science 755, 756 (1993).{/footnote}

The NRC endorsed a "ceiling principle," which would deliberately understate the rareness of a match of genetic markers.{footnote}NRC Report at 13‑14.{/footnote} 

The NRC report has been the subject of much scientific criticism,{footnote}Peter Aldhous, Geneticists Attack NRC Report as Scientifically Flawed, 259 Science 755 (1993); Bernard Devlin et al., Statistical Evaluation of DNA Fingerprinting: A Critique of the NRC’s Report, 259 Science 748 (1993); Bruce S. Weir, Population Genetics in the Forensic DNA Debate, 89 Proc. Nat’l. Acad. Sci. 11654 (1993)Christopher Anderson, Conflict Concerns Disrupt Panels, Cloud Testimony, 355 Nature 753 (1992); Celia Hooper, Rancor Precedes National Academy of Science’s DNA Fingerprinting Report, 4 J. NIH Res. 76 (1992); Leslie Roberts, DNA Fingerprinting: Academy Reports, 256 Science 300 (1992).{/footnote} and the ceiling principle in particular has been described as an unscientific expedient intended to render moot the debate over substructures.{footnote}Eric S. Lander & Bruce Budowle, DNA Fingerprinting Dispute Laid to
Rest, 371 Nature 735 (1994).{/footnote} 

4.  Admissibility in Criminal Cases

Evidence derived from DNA testing has been held generally admissible for the purpose of identifying the perpetrator in a criminal case,{footnote}Perry v. State, 586 So. 2d 242 (Ala. 1991); Prater v. State, 820 S.W.2d 429 (Ark. 1991); Fishback v. State, 851 P.2d 884 (Colo. 1993); Andrews v. State, 533 So. 2d 841 (Fla. 1988); Caldwell v. State, 393 S.E.2d 436 (Ga. 1990); State v. Maltalbo, 828 P.2d 1274 (Haw. 1992); Davidson v. State, 580 N.E.2d 238 (Ind. 1991); State v. Brown, 470 N.W.2d 30 (Iowa 1991); State v. Smith, 807 P.2d 144 (Kan. 1991); Harris v. Commonwealth, 846 S.W.2d 678 (Ky. 1992); State v. Charles, 617 So. 2d 895 (La. 1993); Cobey v. State, 559 A.2d 391 (Md. 1989); Commonwealth v. Lanigan, 641 N.E.2d 1342 (Mass. 1994); State v. Bloom, 516 N.W.2d 159 (Minn. 1994); Polk v. State, 612 So. 2d 381 (Miss. 1992); State v. Davis, 814 S.W.2d 593 (Mo. 1991); State v. Vandebogart, 652 A.2d 671 (N.H. 1994); State v. Duran, 881 P.2d 48 (N.M. 1994); State v. Wesley, 633 N.E.2d 451 (N.Y. 1994); State v. Pennington, 393 S.E.2d 847 (N.C. 1990); State v. Pierce, 597 N.E.2d 107 (Ohio 1992); State v. Herzog, 864 P.2d 1362 (Or. 1993); Commonwealth v. Crews, 640 A.2d 395 (Pa. 1994); State v. Ford, 392 S.E.2d 781 (S.C. 1990); State v. Wimberley 467 N.W.2d 499 (S.D. 1991); Bethune v. State 828 S.W.2d 14 (Tex. 1992); State v. Passino, 640 A.2d 547 (Vt. 1994); Spencer v. Commonwealth, 384 S.E.2d 785 (Va. 1989); State v. Woodall, 385 S.E.2d 253 (W. Va. 1989); Springfield v. State, 860 P.2d 435 (Wyo. 1993). {/footnote} whether using RFLP analysis{footnote}State v. Pennell, Del. Super. LEXIS 520 (1989); State v. Ford, 392 S.E.2d 781 (S.C. 1990) (DNA print testing and the process of RFLP analysis were admissible to prove that DNA in sperm found on victim matched DNA found in blood sample of defendant).
Annot., Admissibility of DNA Identification Evidence, 84 A.L.R.4th 313 § 4 at 335-341(1991).{/footnote} or PCR amplification,{footnote}Annot., Admissibility of DNA Identification Evidence, 84 A.L.R.4th 313 § 4 at 335-341 (1991).{/footnote} though there must be proof that the proper procedures were followed.{footnote}United States v. Two Bulls, 918 F.2d 56 (8th Cir. 1990).
Perry v. State, 586 So. 2d 242 (Ala. 1991); People v. Axell, 1 Cal. Rptr. 2d 411 (Cal. Ct. App. 1991); People v. Barney, 10 Cal. Rptr. 2d 731 (1992); People v. Fishback, 829 P.2d 489 (Colo. Ct. App. 1992); Smith v. Deppish, 807 P.2d 144 (Kan. 1991); People v. Castro, 545 N.Y.S.2d 985, 999 (N.Y. Sup. Ct. 1989).{/footnote}  A number of courts have held that statistical evidence derived from DNA testing enjoys a sufficient degree of acceptance to render such evidence admissible{footnote}United States v. Jakobetz, 955 F.2d 786 (2nd Cir. 1992).
People v. Soto, 35 Cal. Rptr. 2d 846 (Cal. Ct. App. 1994); Martinez v. State, 549 So. 2d 694 (Fla. Dist. Ct. App. 1989).{/footnote} and some have specifically approved the "ceiling principle" approach, discussed above.{footnote}Commonwealth v. Lanigan, 641 N.E.2d 1342 (Mass. 1994); State v. Vandebogart, 652 A.2d 671, 678 (N.H. 1994); State v. Cauthron, 846 P.2d 502, 517 (Wash. 1993).{/footnote}

Some states have taken judicial notice that DNA test results are generally accepted as reliable in the scientific community, provided the laboratory has followed accepted testing procedures.{footnote}Hayes v. State, 660 So. 2d 257, 264 (Fla. 1995).{/footnote}

Some courts, on the other hand, have held that the reliability of DNA identification techniques is not yet sufficiently accepted in the scientific community for it to be admissible in a criminal case.{footnote}State v. Bible, No. Cr-90-0167-AP, 1993 WL 306544 (Ariz. filed Aug. 12, 1993) (en banc); People v. Wallace, 17 Cal. Rptr. 2d 721 (Cal. Ct. App. 1993); People v. Barney, 10 Cal. Rptr. 2d 731 (Cal. Ct. App. 1992); United States v. Porter, 618 A.2d 629 (D.C. 1992); People v. Atoigue, No. CR91-95A, 1992 WL 245628 (Guam Dist. Ct. App. Div. Sept. 11, 1992); Commonwealth v. Curnin, 565 N.E.2d 440 (Mass. 1991); Commonwealth v. Lanigan, 596 N.E.2d 311 (Mass. 1992); State v. Schwartz, 447 N.W.2d 422 (Minn. 1989); State v. Vandebogart, 616 A.2d 843 (N.H. 1992); State v. Anderson, 853 P.2d 135 (N.M. Ct. App. 1993); People v. Castro, 545 N.Y.S.2d 985 (N.Y. Sup. Ct. 1989); People v. Keene, 591 N.Y.S.2d 733 (N.Y. Sup. Ct. 1992).{/footnote}  Some courts  have also held that statistical evidence derived from such techniques is not sufficiently accepted.{footnote}United States v. Porter, 618 A.2d 629 (D.C. Cir. 1992); United States v. Yee, 134 F.R.D. 161 (N.D. Ohio 1991).
State v. Bible, 858 P.2d 1152 (Ariz. 1993); People v. Barney, 10 Cal. Rptr. 2d 731 (Cal. Ct. App. 1992) (discussing NRC report); State v. Watson, 629 N.E.2d 634 (Ill. App. Ct. 1994); Commonwealth v. Curnin, 565 N.E.2d 440, 442 (Mass. 1991) (finding "no demonstrated general acceptance or inherent rationality of the process by which Cellmark arrived at its conclusion that one Caucasian in 59,000,000 would have the DNA components disclosed by the test . . ..[T]here is no showing . . . that scientists agree generally that the distribution of the alleles disclosed in Cellmark’s testing is random in the Caucasian population so as to warrant the calculations"); State v. Cauthron, 846 P.2d 502 (Wash. 1993).{/footnote}
It has been held that for statistical evidence to be admissible, the expert must, at the very least, demonstrate a sufficient knowledge of the relevant database grounded in the study of authoritative sources.{footnote}Murray v. Florida, No. 83-556 (Fla. Supr. 4/17/97) (excluding statistical testimony due to inadequate foundation; noting that expert need not have helped to assemble the database used).
See also Commonwealth v. Curnin, 565 N.E.2d 440, 442 (Mass. 1991) (expert witness held not qualified to give an opinion as to the statistical methodology employed by independent laboratory).{/footnote}

6.  Admissibility to Prove Paternity

The use of DNA in paternity cases involves a comparison of a sample of the father’s DNA and a sample of the child’s DNA.  DNA evidence is rendered admissible by statute to prove paternity in some states.{footnote}E.g., Conn. Stat. § 46b-168; Mich. Stat. Ann. § 25.496 (1996); Rev. Stat. Mo. § 210.817 (Uniform Parentage Act); Mont. Code Ann. § 40-5-201 (1995);  Mont. Code Ann. ’40-6-102 (Uniform Parentage Act); N.M. Stat. Ann. § 40-11-13; N.Y. CLS Family Ct. Act § 418 (1996);  Or. Rev. Stat. § 109.51 (1995) (Uniform Act on Blood Tests to Determine Paternity); 23 Pa. Cons. Stat. 4343 provides:
            Genetic test results indicating a 99% or greater probability that the alleged father is the father of the child shall create a presumption of paternity which may be rebutted only by clear and convincing evidence that the results of the genetic tests are not reliable in that particular case.{/footnote}  Courts in other states have held DNA typing evidence admissible to prove paternity.{footnote}State v. Simien, 677 So.2d 1138 (La. App. 1996); Johnson v. Meehan, 461 S.E.2d 369, 370 (N.C. App. 1995).
CHECK State Dep’t of Social Serv. v. Bradley, 673 So.2d 1247 (La. App. 1996).{/footnote}

Bibliography

§ 1.  Generally

Thomas M. Fleming, Annotation, Admissibility of DNA Identification Evidence, 84 A.L.R. 4th 313 (1991).
John McCabe, DNA Fingerprinting: The Failings of Frye, 16 N.Ill.U. L.Rev. 455 (1996).
Anthony Pearsall, Comment, DNA Printing: The Unexamined Witness, 77 Cal. L. Rev. 665 (1989).
Rorie Sherman, DNA Unraveling, Nat’l L.J., Feb. 1, 1991, at 1.
William C. Thompson, Evaluating The Admissibility Of New Genetic Identification Tests: Lessons from The "DNA War," 84 J. Crim. L. 22 (1993).
William C. Thompson & Simon Ford, DNATesting: Debate Update, Trial, Apr. 1992, at 52 .
Judicial Tide Turns Against Admission of FBI’s DNA Tests, 7 BNA Crim. Prac. Man. 16 (1993).
DNA Typing Critics Say Report Validates Their Concerns, 6 BNA Crim. Prac. Man. 195 (1992).

§ 2.  Scientific Literature

Christopher Anderson, DNA Fingerprinting Discord, 354 Nature 500 (1991).
Leslie Roberts, Fight Erupts Over DNA Fingerprinting, 254 Science 1721 (1991).
Peter Neufeld & Neville Colman, When Science Takes the Witness Stand, 262 Sci. Am. 46(1990).
William C. Thompson & Simon Ford, Is DNA Fingerprinting Ready for the Courts?, 125 New Scientist 38 (1990).
Eric S. Lander, DNA Fingerprinting On Trial, 339 Nature 501 (1989).