Genomics in the Courtroom: The Current Landscape of DNA Technology in Criminal and Civil Litigation.

AuthorElder, Scott

ADVANCES in genetic technology have led to large and lasting impacts on the law, dating back to the late nineteen-eighties and continuing to today. Recently, at-home genetic testing led to the high-profile arrest and criminal conviction of a seventy-year-old serial killer. That individual terrorized California communities in the sixties and seventies until a familial match in an open-source DNA database narrowed the suspect list, ultimately leading police to the killer.

The impact of new and more-widely available technologies extends beyond criminal law and into civil litigation. As plaintiff and defense counsel employ technological innovations to support causation and damage claims, counsel and the courts are confronting new issues involving the nature of genetic testing, privacy, and admissibility. As they do so, they are learning the litigation pros and cons of developing this evidence.

This article considers the nature of these impacts. We begin with a short review of the basics of DNA. Next, we look at examples of new DNA technology. Finally, we examine how DNA technology is being used in the courtroom.

  1. The (Very) Basics of DNA Sequencing

    Deoxyribonucleic acid--DNA for short--functions as the playbook to human development. (1)DNA molecules are made of two twisting, paired strands forming the familiar double-helix. Each strand is composed of a sequence of four different chemical units referred to as the bases--adenine, thymine, guanine, and cytosin. Bases on opposite strands pair in a specific manner--A's pair with T's and C's pair with G's. The sequence of A-T pairings and G-C pairings determines how our DNA "reads" and, in turn, who we are. The full suite of DNA--billions of DNA pairings--comprises the human genome. Specific units of DNA, or genes, create specific proteins, which serve as the building blocks for everything in the human body and direct signals throughout our bodies. Mutated DNA creates abnormal proteins that can lead to diseases such as cancer.

    DNA sequencing is the process of determining the order of A, T, G, and C bases in a strand of DNA. (2) Common sequencing processes begin with nucleotides--the building blocks of DNA that consist of a base (an A,G,C or T) together with a molecule of sugar and of phosphoric acid. Scientists "tag" nucleotides chemically and place the tags into a new DNA strand generated from the DNA the analyst wants to analyze. A specific light source activates the chemical "tag", which allows researchers to determine the sequence (the order of A,G,C and T) of the strand of interest. This detailed and laborious process is necessary to ensure accuracy. Once scientists determine the sequence, they use this information to look for variations or mutations in an individual's genes. Harmful variations or mutations can be as simple as a substitution of one base or as vast as the complete absence of thousands of bases.

  2. DNA Test Kits and Open-Source Databases: The Advent of At-Home Testing

    Companies like 23andMe and Ancestry have brought once-novel and cost-prohibitive genetic tests to the masses.(3) Home test-kits instruct purchasers on extracting saliva samples and sending them off for testing for a variety of purposes, including to determine health risks and genealogy. Companies make these determinations through a process known as genotyping, which zeroes in on specific DNA markers--or variants--that indicate a person's health risks or family history. For example, 23andMe divides its testing services into five categories: Health Predispositions; Wellness; Traits; Carrier Status; and Ancestry. (4)

    Ancestry offers similar services. (5) Initially, the company focused on genealogy--allowing users to track family lineage. Ancestry later entered the DNA test-kit industry in order to provide more detailed estimates of lineage, migration patterns, and certain genetic attributes by supplementing the process with an individual's genetic information. Customers can use Ancestry Health to discover personal and family health issues.

    Unlike the commercial offerings from Ancestry and 23andMe, open-source databases, such as and others, allow individual users to upload their genetic profile to compare with other users. (6) Users must first determine their genetic profile in order to upload that information. Commercial testing kits, including those from 23andMe and Ancestry, allow users to create a DNA profile to upload.(7) Once the profile is in the system, the databases can compare profiles and enable individuals to find distant, or long-lost, relatives. But there is a catch. Open source means what it says, and database companies like warn users that their genetic profile might be used for other purposes. (8) More on that below.

  3. The Golden State Killer

    In April 2018, police arrested Joseph DeAngelo, a seventy-year-old former police officer, at his home in California. Police believed that DeAngelo was the serial killer dubbed the "Golden State Killer." The Golden State Killer had terrorized California in the seventies and eighties by committing a series of horrific sexual assaults and murders. (9) Naturally, arresting a man who had terrorized those communities made national headlines. But the way police identified DeAngelo after decades of trying drove public interest long after his arrest.

    Police developed the killer's DNA profile from samples left at different crime scenes, which were preserved until advances in technology allowed scientists to analyze them. Police ran the profile through...

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