DNA Technology's Impact on the American Criminal Justice System

Introduction and Overview

This research investigates the way DNA technology has affected America's criminal justice system by detailing its uses as well as the challenges that still lie ahead. Utilizing secondary resources—including the testimonies of several experts in the field, among them the Director of the Virginia Division of Forensic Science, the Executive Director of the National Commission on the Future of DNA Evidence, and the Assistant Director for the Laboratory Division of the Federal Bureau of Investigation—as well as published resources from other experts, this paper seeks to answer the question of how DNA has impacted America's criminal justice system.

The purpose of this research is to show that DNA evidence has positively changed the judicial system, despite the challenges it continues to face. The intent is to use this research to better understand the importance of DNA technology in order to promote its use both pre- and post-conviction.

For one to fully understand the impact DNA has had on the criminal justice system in the United States, it is imperative to have a general knowledge of DNA and the history of its use in the system. This section presents an overview of DNA as an introduction to the topic and concludes with the historic development of DNA as a means of genetic forensics and criminal profiling.

DNA is organized as two complementary strands linked together with bonds that can be separated. Each strand of DNA is a chemically linked chain of nucleotides, which are made up of a sugar, a phosphate, and one of four kinds of nucleobases—often simply referred to as bases. These bases are adenine, thymine, guanine, and cytosine, abbreviated as A, T, C, and G. Furthermore, these bases only pair up properly with one other base: A with T and C with G, and vice versa, on their complementary strand (DNA).

The order in which these pairs occur is relevant. A + T is not the same as T + A. However, since there is only one possible mate for every base, naming only the base on the conventionally chosen side of the DNA strand is sufficient to describe its sequence. Replication is performed by splitting the double strand down the middle via a chemical reaction. The two single strands then seek out their proper mate from a pool of the four bases. Because each base has only one correct complementary base, each single strand replicates the double strand perfectly, unless a mutation occurs (DNA). It is the unique arrangement of the components of an individual's DNA that the judicial system has turned to in order to help identify criminals.

DNA as an Investigative Tool for Law Enforcement

DNA, as one of law enforcement's investigative tools, was first introduced into the courtroom in the late 1980s. It was used not only to convict criminals of crimes but also to free those who had been wrongly imprisoned. "By mid-1999, more than 60 people had been released from American prisons following post-conviction analysis of DNA evidence. Many of them had already served a number of years behind bars" (Langeneckert).

When creating a DNA profile, a sample of the individual's cells is first collected, typically from blood, tissue, or saliva. From this sample, a DNA molecule is removed and purified. It is then cut and processed to reveal the individual's unique pattern. Once this pattern is established, it can be compared with DNA samples from the crime scene in criminal cases (Langeneckert).

Initially, the reliability of DNA evidence was questioned; however, by the end of the 1990s a number of advances improved the consistency of the data. These advances included comparing a greater number of sites on the DNA molecules, rendering a DNA match effectively 100% conclusive. In addition, enhanced technology began to allow for much smaller sample sizes than ever before. Even the smallest "amounts of saliva, such as those found on the rim of a coffee cup or the back of a postage stamp, were enough to be analyzed and used as evidence" (Langeneckert). These advancements saw DNA profiling become more and more commonly used in the American justice system.

To establish a DNA "fingerprint" that is unique to the individual, DNA is first extracted from the chromosomes in the nucleus of a cell from the collected sample. The DNA is then cut into fragments using any one of a group of special restriction enzymes. These enzymes cut the DNA only at specific cutting sites, and it is this pattern of cutting sites—inherited from one's parents—that forms the beginning of a genetic profile (Levine).

The National DNA Index System

Recognizing the value of collecting DNA information for investigative purposes, the Federal Bureau of Investigation launched a program in October 1998 known as the National DNA Index System (NDIS). This nationwide computer database seeks to capitalize on the crime-solving potential of DNA by allowing states to submit samples of DNA from convicted criminals and unknown persons identified at crime scenes. These samples can then be cross-referenced to help prosecute criminals. Only three months after its inception, the NDIS had been used approximately 200 times to solve crimes (Langeneckert).

The database expanded as all fifty states joined the system. However, "although all states had laws requiring at least some convicted criminals to provide DNA samples, many did not have the resources needed to collect and process them" (Langeneckert). For this reason, the NDIS has not grown as quickly or been used as efficiently as its creators had hoped.

Despite the early success of the program in capturing hundreds of criminals, fewer than one-third of the states were submitting their DNA samples to the NDIS. To complicate matters further, there was a backlog of more than 400,000 DNA samples that had been collected but had not yet been processed. This was in addition to 200,000 samples that needed to be retested due to advancements in technology (Langeneckert). This delay in using the database to its fullest potential has slowed the effectiveness of forensic genetics.

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