Articles

What litigators should know about DNA testing

By James R. Wronko
New Jersey Lawyer May 5, 1995

Quickly, name the latest and most hyped revolution in the use of scientific evidence in the courtroom. No contest: DNA testing wins hands down. DNA testing has the ability to provide the definitive answer to a myriad of issues that arise across the legal spectrum. DNA testing can allow a scientist to exclude a person as a potential donor of biological material or include that person as one of a certain percentage of the population that could be the source of the material. To its many unabashedly fervent proponents, DNA testing can do no wrong. Proponents have referred to it in glowing terms, declaring for example, "If you are a criminal, it's like leaving your name, address, and Social Security number at the scene of the crime. It's that precise."

Despite its many accolades, DNA testing is not without its flaws and raises several serious issues.

Although DNA testing recently came to the forefront because of its role in People v. 0.J. Simpson, it had been extensively used prior to the Simpson case. DNA testing first appeared in an American courtroom in 1986 and has now become commonplace. At present. at least 41 states have reported decisions that uphold the admissibility of DNA test results as evidence in criminal trials. DNA testing has been used to convict and even execute criminals. It also has exonerated individuals erroneously convicted of rapes that occurred years prior to the advent of DNA testing.

In New Jersey. DNA evidence has been introduced in criminal trials in approximately half of the 21 counties, with several courts even taking judicial notice of its admissibility and dispensing with the necessity of conducting a pretrial Frye hearing. The New Jersey State Police recently Itegan accepting cases for DNA testing using the PCR method. one of the two commonly used forms of DNA testing. It is anticipated, therefore. that the criminal courts will experience a dramatic increase of DNA cases. This explosion is bound to spill over into the civil arena. Thus, it is essential that contemporary legal practitioners become familiar with its attributes.

Characteristics of DNA

DNA testing implicates the disciplines of human and population genetics, bio-chemistry and molecular biology. Although DNA testing is relatively modem, it is based upon DNA or deoxyribonucleic acid, which was first discovered in 1886 and its basic structure ascertained in 1953.

DNA is located in each cell in the human body, except red blood cells. DNA can be extracted from blood, semen, hair follicles, body tissue, saliva, urine and bone material. Each person possesses a unique DNA, with the exception of an identical twin. DNA is consistent in one's entire cell structure and remains constant throughout one's lifetime DNA located in an infant's body tissue at birth is identical to the DNA in his blood or hair follicles at age 90.

DNA contains the genetic makeup of each person and regulates the individual characteristics that all human beings possess such as height, facial structure and eye color. DNA varies little from one person to the next, as the similarities among people far outweigh the differences. DNA testing focuses upon the regions of the DNA molecule where the individual characteristics are located. These areas are referred to as polymorphic regions.

Two primary DNA tests are currently available to litigants. The first test, introduced in 1986, is Restriction Fragment Length Polymorphism (RFLP), commonly known as DNA fingerprinting. The second test, introduced in 1988 and made commercially available via a marketing kit in 1990. is the Polymerase Chain Reaction (PCR) method, or amplification test.

The initial procedures involved in both the RFLP and PCR tests are identical. First, cellular material is removed from the item to be tested and the DNA contained within the cells is extracted and isolated. Once the DNA has been isolated, the examiner can choose to do either or both tests[',, depending on the quantity and quality of the available DNA.

The RFLP test consists of a method in which the existing DNA, which resembles an extremely long spiral staircase, is cut by synthetic chemicals called restriction enzymes into small segments known as restriction fragments. These restriction fragments vary in length in the polymorphic regions from person to person. The fragments are transferred onto a gel and separated by size.

Essentially, the fragments are subject to electric magnetism that acts to pull the shorter DNA segments to one end of the gel faster than the larger segments. The DNA fragments are transferred onto a nylon membrane where they are hybridized or paired with a genetic probe, which contains synthetic DNA. These probes detect and illuminate the polymorphic regions. The finished product resembles the bar codes on common consumer products. The lengths in the various polymorphic regions from the samples being tested are compared to find out whether a match exists or not. At the risk of over simplification, if the lengths are the same size, a match is declared.

PCR method

The PCR method focuses on a particular region of the DNA molecule, most commonly the DQ Alpha gene, and replicates the DNA in that gene until enough copies are made to allow its type to be ascertained. Theoretically, when using the PCR method, DNA from a single cell can be reproduced sufficiently for its type to be identified. The extracted DNA is placed into a heating block, or Thermal Cycles. and run through a cycle in which the DNA is subjected to varying temperatures.

During each cycle the DNA in the region being examined is doubled. The yield for a 30-cycle amplification is generally about 10 copies of the original DNA sequence. The amplified quantity of DNA is placed onto a typing strip containing synthetic DQ Alpha DNA and placed into another heating device, called a water bath, and subjected to a heating process in which the genotype ot the DNA is ascertained. For example, the DQ Alpha gene has six possible alJeles, or traits. Each person has two alleles. one inherited from each parent. In total, there exist 36 genotypes that any one individual can possess. The genotype obtained can be compared to that of other DNA in order to decide whether a match exists.

Major differences exist between the two tests. It takes eight to 12 weeks to conduct RFLP testing while PCR testing can take as little as one to three days. PCR testing generally requires only 10 percent of the biological material that RFLP requires and is 1,000 times more sensitive. In fact, PCR testing has been performed on DNA recovered from Egyptian mummies, the Dead Sea Scrolls and extinct animals.

A significant difference is the discriminating power of the two tests. RFLP can determine a genetic profile that can be exclusive to one out of 3 billion people. As there are only 6 billion people in the world, this result provides virtually an absolute assurance that the questioned DNA originated from the known individual. In contrast, PCR testing is considerably less precise. Generally, the genetic profile revealed by the PCR test

is exclusive to 0.1 percent to 10 per-cent of the population. This percentage will decrease, and the test will become more precise as different genes are adapted for PCR testing.

Civil applications

DNA testing can be favorably applied to civil as well as criminal cases. The application of DNA testing is limited only by an attorney's imagination. In immigration law, for example, DNA testing could be used to resolve the issue of whether an applicant is a blood relative of a United States citizen. It could resolve life insurance and probate disputes regarding proof of death of the insured and may be utilized to identify missing persons.

DNA paternity testing represents a major advancement over traditional scientific testing. The New Jersey Parentage Act, N.J.S.A. 9:17-51, has authorized DNA paternity testing, which is able to exclude a man as the father of a child, as well as include him, almost to the point of establishing paternity, as one of a minute percentage of the population who could be the biological father. DNA paternity testing can be used prior to the birth of a child to allow for the early resolution of paternity issues in cases involving rape or multiple partners. A major advantage of DNA paternity testing is that it is not dependent upon obtaining a blood sampIe. Skeletal remains could be used to test for paternity. In fact, researchers are currently using the PCR method to attempt to determine the bloodlines of the ancient Egyptian pharaohs.

The PCR method also has been utilized to conduct DNA typing on saliva from cigarette butts and envelopes. By using DNA testing, a litigant could prove, based upon discarded cigarette butts, that a particular person had been in a certain place, or use saliva on an envelope to prove that a person had mailed a letter. In addition, a bloodstain deposited in the interior of a vehicle during a multi-passenger car accident could be tested to determine who was operating the vehicle at the time of the accident.

Crucial link

The application of DNA testing in criminal cases is legion. In the opinion of certain individuals, DNA testing can literally decide guilt or innocence. By comparing biological evidence left at the scene of a crime to a suspect's sample, one could conclusively link a suspect to a crime scene or a key piece of evidence. The criminal who leaves behind hair. blood, semen or even a smoked cigarette is, in fact, leaving behind a tangible piece of his identity. Through DNA testing, prosecutors. juries and defense attorneys can conclusively determine whether the rapist who ejaculates into his victim's vagina or the murderer whose hair or skin remains under the fingernails of the victim is the accused.

Although DNA testing is thought to be one of a prosecutor's most potent weapons, in reality, it can be an innocent defendant's best hope of acquittal. The opportunity that DNA testing presents to the criminal defense bar is remarkable. In the United States and United Kingdom, DNA testing has resulted in one-third of potential suspects excluded as donors of allegedly incriminating evidence. In the great majority of cases, an exclusion almost fully guarantees a dismissal by the prosecutor or a not-guilty verdict. Indeed, in the United States, only two cases exist in which a jury returned a criminal conviction despite a DNA test result that excluded the defendant as the donor of key biological evidence. One of the two cases was State V. DeMarco, a case the author prosecuted while an assistant Somerset County prosecutor.

In DeMarco, various national DNA experts, including Edward Blake, a member of the O.J. Simpson defense team, testified that based upon PCR test results, spermatozoa deposited in the oral cavity of a murder victim, ostensibly by her killer, did not originate from the defendant. The jury disregarded the DNA evidence and relied upon strong circumstantial evidence to return a verdict of guilty. DeMarco is instructive because it demonstrates that PCR test results often are not what they appear to be, especially when extremely small quantities are tested. In DeMarco, the amount of DNA tested consisted of less than two nanograms, or two-billionths of a gram.

In past court proceedings. parties adverse to Blake's findings deferred to his expertise and neglected to attempt a systematic challenge of his methodology. In DeMarco, however, the prosecution was able to obtain and analyze reports and testimony from approximately 45 of Blake's cases. The prosecution discovered instances of unexplained contamination in approximately one-third of the tests performed by Blake. This was not surprising as samples consisting of only a few nanograms of DNA are readily susceptible to contamination, which is replicated along with the original genetic material.

The jury also was informed that the biological evidence was tested three times by three different laboratories, with the third laboratory result different from the first. As a result of the concerted efforts by the pnosecution to attack Blake's findings, the jury was able to disregard his testimony.

The DeMarco case demonstrates that the advent of DNA testing and the opportunities it presents to both the civil and criminal litigant is not without some peril. Several issues exist that can only be resolved over tirne. One such issue is the risk that juries and courts will blindly follow the opinions offered by qualified and unqualified DNA experts, most of whom are not subject to any governmental licensing or regulation. Another concern is that the expense involved in litigating a case involving DNA testing could inure to the benefit of the party with deep pockets. as that party's adversaries may not be able to afford their own 'referee" test or hire the expensive and limited number of experts willing to testify in DNA cases.

A third concern is the lack of uniform standards to which testing laboratories must adhere in collecting, preserving and testing biological evidence. as well as a lack of training on the part of investigative personnel who collect and preserve this highly sensitive evidence. A possibility exists that DNA technology has outpaced the ability of law enforcement officers to properly collect and store biological material.

A final issue that is becoming more prominent is the privacy concerns surrounding the enactment of statutes seeking to establish data banks of DNA from convicted sex offenders. (See, e.g., New Jersey Public Law 1994, Chapter 136 (Oct. 31, 1994.) The day could come when the DNA makeup of every child would be recorded at birth and stored in a national data bank.

The advent of DNA testing in the courtroom makes it imperative that attorneys who engage in litigation become familiar with and be able to defend their clients against DNA evidence, which could be viewed as often dispositive. Litigators must be aware that DNA testing is only as reliable as the corresponding competence of the technician and testing laboratory, and that DNA evidence is effective only when explained properly or presented to a jury or court by an attorney who has taken the time to understand it.

The contemporary attorney must realize this is a developing area of the law. In time, standards will evolve and the precision of the test will be enhanced. Although societal concerns about privacy may limit certain applications of the DNA test procedures, attorneys must keep abreast of these changes or risk being left behind.

James R. Wronko, a partner in the Somerville firm Wronko, O'Hara & Miller, is a former assistant Somerset County prosecutor and deputy attorney general with the N.J. Division of Criminal Justice. He is one of only two prosecuting attorneys in the United States to obtain a conviction despite DNA evidence that excluded the suspect.