DNA Evidence Challenges in Georgia Criminal Cases

DNA evidence carries significant weight in many Georgia criminal cases, but it is not automatically admissible simply because testing was performed. Before a jury can consider DNA results, the evidence must clear several distinct legal hurdles: a proper foundation, an intact chain of custody, and, since 2022, a Daubert reliability analysis of the underlying scientific methodology. Each of these hurdles addresses a different potential weakness in how DNA evidence reaches the courtroom.

Establishing a Foundation

Before DNA evidence can be admitted, the prosecution must establish a proper foundation. This includes identifying the sample being tested, describing the testing laboratory’s accreditation and protocols, and establishing the qualifications of the analyst who performed or interpreted the testing. Without this foundational showing, DNA results cannot be properly introduced regardless of how reliable the underlying science might be in the abstract.

Chain of Custody

A separate but related challenge involves the chain of custody, the documented chain of possession showing that a sample remained in substantially the same condition from the time it was collected to the time it was tested. Gaps in this chain do not automatically make DNA evidence inadmissible; in most circumstances, such gaps go to the weight a jury should give the evidence rather than barring its admission outright. However, where a chain-of-custody objection is properly raised and the gap is significant enough to call into question whether the evidence is in substantially the same condition as when it was collected, that failure can affect whether the evidence is admitted at all. The distinction between a chain-of-custody problem (a question of authentication) and a challenge to the underlying science (a question of reliability) is an important one, because the two types of challenges are evaluated differently.

Daubert Reliability Review

Since House Bill 478 took effect on July 1, 2022, O.C.G.A. § 24-7-702 applies Daubert-style reliability gatekeeping to expert testimony in Georgia criminal cases, including DNA methodology. Under this framework, courts consider factors such as whether the technique can be and has been tested, whether it has been subject to peer review and publication, its known or potential error rate, and whether it is generally accepted within the relevant scientific community. This extension of Daubert to criminal cases gives defendants a tool to challenge DNA testing methodology itself, separate from challenges to how a particular sample was handled.

The Role of the Georgia Bureau of Investigation

The Georgia Bureau of Investigation’s Division of Forensic Sciences serves as the primary state laboratory responsible for much of the DNA testing used in Georgia criminal cases. The laboratory’s accreditation status and its evidence submission protocols are relevant considerations when a foundation challenge is raised, since the prosecution’s foundational showing typically relies on establishing that the laboratory followed its accredited procedures.

Post-Conviction DNA Testing

O.C.G.A. § 35-3-160 addresses DNA analysis in connection with felony convictions and certain other charges, establishing rights related to testing after a conviction has already occurred. This provision operates separately from the admissibility challenges that arise during the original prosecution, addressing instead the availability of testing as part of post-conviction review.

Common Points of Challenge

Beyond the foundational, chain-of-custody, and Daubert frameworks described above, several recurring technical issues tend to arise in DNA evidence challenges. These include contamination during collection or testing, degraded samples that complicate accurate analysis, the interpretation of mixed DNA profiles involving more than one contributor, the reliability of probabilistic genotyping software used to interpret complex samples, and the error rates associated with individual analysts or laboratory procedures. Each of these points can form the basis of a challenge under either the foundational/chain-of-custody framework or the Daubert reliability framework, depending on what aspect of the evidence is being questioned.

Why These Distinctions Matter

Understanding that DNA evidence can be challenged on three conceptually different grounds, foundation and authentication, chain of custody, and underlying scientific reliability, clarifies why a single piece of DNA evidence might survive one type of challenge while remaining vulnerable to another. Since 2022, Georgia’s adoption of the Daubert framework for criminal cases has given the scientific-reliability challenge a clearer statutory basis than existed under the prior standard.

This article provides general information about Georgia law and is not legal advice. Consult a licensed Georgia attorney about a specific situation.