DNA databases: when fear goes too far.

AuthorPeterson, Rebecca Sasser

    Experience should teach us to be most on our guard to protect liberty when the Government's purposes are beneficent. Men born to freedom are naturally alert to repel invasion of their liberty by evil-minded rulers. The greatest dangers to liberty lurk in insidious encroachment by men of zeal, well-meaning but without understanding.(1)

    Following the highly publicized trial of O.J. Simpson, DNA evidence has become a common feature in American criminal trials. As a forensic tool, DNA analysis was initially used to link an already known suspect to a particular crime scene. In these situations, law enforcement officers obtain DNA from the suspect and compare it to DNA recovered from the crime scene. While this direct analysis of a known suspect's DNA is still widespread, a new forensic use has developed. With the development of DNA databases, states are obtaining DNA samples from people convicted of specific crimes and then storing the resulting DNA "fingerprint" in a computer database.(2) When a crime occurs in which DNA evidence is recovered, police compare that sample against every previously obtained DNA fingerprint in the database, hoping to find a match, or "cold hit." This procedure, and DNA databases generally, allows law enforcement to use DNA in the initial stage of an investigation to identify a suspect.

    The potential use of DNA to identify the offender in every crime where DNA evidence is recovered has caused some commentators to christen DNA fingerprinting as "the single biggest advancement in forensic science."(3) Optimal effectiveness, however, would require a universal DNA database that contains DNA fingerprint of every citizen, otherwise potential matches would be missed.(4) Some argue that a universal DNA database, in addition to solving crimes, would deter crimes because people would be unlikely to commit crimes knowing that the likelihood of being conclusively identified through a quick search in a DNA database was nearly one-hundred percent.(5)

    This Note discusses the efficacy of developing a universal DNA database by asking a larger question: how far are we as a society prepared to go in allowing the government to impede our liberty and our privacy in the name of crime prevention. Is there a limit, constitutionally or theoretically, to what the government can do when it is acting in its role as the preventive state?(6) Have we, as a citizenry, become so terrified of crime that we are willing to suspend our concept of ourselves as a free and autonomous population? Have we as a citizenry, become so terrified of crime that we are willing to allow the government to infringe on every person's freedom by requiring citizens to provide DNA samples?

    Part II of this Note provides a description of DNA and of the most common testing procedure used to produce a DNA fingerprint. Part III discusses the composition of the existing offender DNA databases and of a potential universal DNA database. Part IV examines the constitutionality of both types of DNA databases. Concentrating on Fourth Amendment search and seizure analysis, this Section first considers how collection of DNA for the existing offender DNA databases survived Fourth Amendment scrutiny and then discusses whether developing a universal DNA database also would withstand constitutional scrutiny, concluding that developing a universal database would be found unconstitutional in light of society's stronger privacy concerns. Part V explores why the development of a universal database, in addition to its constitutional inadequacy, would be ill-advised because of additional policy concerns regarding the expansion of a preventive state. While nearly total crime detection might be possible, this Note concludes that this benefit could be obtained only at an unreasonable cost to our society's concepts of privacy, freedom, and the appropriate role of the government when acting to prevent rather than punish crime.


    To understand why DNA is such an effective forensic identification tool, it is necessary to first discuss the DNA molecule itself. Part A briefly describes the DNA molecule, and explains why it is such a powerful means of identification. Part B describes the most common technique of DNA fingerprinting for forensic identification purposes, Restriction Fragment Length Polymorphism analysis.

    1. The DNA Molecule

      Deoxyribonucleic acid (DNA) is a long chemical strand found in the nucleus of almost every cell in living organisms.(7) The DNA molecule is essentially the "blueprint" for the physical make-up of each individual; it determines every physical characteristic from height to eye color.(8) A DNA molecule consists of two twisted strands of alternating units of phosphates and sugars connected, like rungs on a ladder, by complementary nucleotide base pairs.(9) Among the four nucleotide bases, Adenine (A), Thymine (T), Cytosine (C) and Guanine (G), A only links with T, and C only links with G.(10)

      DNA is found on the twenty-three chromosomes a person inherits from each parent. Since these DNA sequences code for the characteristics that make us human, i.e., two hands, two eyes, two legs, etc., approximately ninety-nine percent of an individual's DNA is identical to all other humans.(11) However, the remaining one percent of the DNA sequences vary from person to person. Within these sections of DNA, sequences of base pairs are often repeated hundreds or even thousands of times. Such sequences are called Variable Number of Tandem Repeats ("VNTRs").(12) Because the pattern of VNTRs is different for everyone, examination of these polymorphic sections allow an individual to be identified.(13)

    2. DNA Fingerprinting

      While there are at least two other types of DNA analysis that may be used to identify individuals, RFLP is currently the most commonly employed.(14) The theory behind RFLP analysis is that by examining the length of VNTRs at various sites, or "loci," one can determine whether a particular sample of DNA came from a known source.

      In RFLP analysis,(15) first DNA is extracted either from an individual, or from evidence, such as blood or skin, obtained at a crime scene.(16) The extracted DNA is then digested by an enzyme that cuts the chain wherever it contacts a particular known sequence. The result is numerous DNA fragments of varying lengths.(17) Because the length of VNTRs in individuals varies, the enzyme will cut at different lengths for different people. The fragmented DNA is then placed on a slab of gelatin-like material known as agarose gel. An electric current is applied to the gel which causes the fragments to separate and move across the gel at varying speeds, depending on the length of the fragment. Shorter, lighter fragments travel further across the gel than longer, heavier fragments.(18) These fragments are then transferred in their exact positions from the gel to a nylon membrane.(19) Radioactive markers are then applied to the DNA fragments on the membrane and exposed to a sheet of film. The result is an autorad,(20) the exposed films depiction of the banding pattern of the DNA, which creates a UPC-like bar code as found on items in retail stores. This banding pattern is the DNA fingerprint that can be digitalized and stored in a database for future use.

      The DNA fingerprint is then compared to a known sample of DNA. If the DNA was from the same source, fragments of the same length should appear as bands on the same place on the autorad. A visual match is verified by a computer measurement of the digitized pattern which determines the two samples to be a match if they fall within a specified match window of measurement variation.(21)

      Once a match has been identified, the examiner must determine the statistical probability that this particular profile occurs in a particular population.(22) Generally this is done through the "product rule" in which the probability that one person in a particular population would display this banding pattern in one probe is multiplied by the probability that another person in the same population would display the same pattern for a second probe.(23) In a criminal trial, the result might be explained by an expert in statistical probabilities as "[t]he probability of selecting at random from the population an unrelated individual having a DNA profile matching the [defendant's] is approximately 1 in 200,000 in African Americans, 1 in 200,000 in Whites, and 1 in 100,000 in Hispanics."(24)

      It is important to note that the only information obtainable about an individual genetic sequence from a DNA fingerprint created through RFLP analysis is whether two samples originated from the same person. The DNA fingerprint itself does not contain any information about the individual's eye color, race, sex, or risk of genetic disease.(25)


    Although the primary concern of this Note is the development of a potential universal DNA database containing DNA fingerprints from every individual, to understand the constitutional and policy implications of a universal database it is first necessary to consider existing DNA databases presently limited to criminal offenders.

    1. Offender DNA Databases

      With the increased use of DNA evidence in criminal trials to link the defendant to the crime scene, a movement to use DNA in the investigative stage to identify potential suspects has gained momentum. England was the first country to develop a large-scale database for this purpose.(26) To identify as many suspects as possible, England requires samples to be taken from anyone charged with a "recordable offense."(27)

      While the United States has progressed more slowly in creating DNA databases for criminal offenders, the passage of the DNA Identification Act of 1994(28) spurred the movement by creating a national offender DNA database administered by the FBI and by offering financial incentives for states to create...

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