A blood test can be one of the strongest pieces of evidence in a Georgia DUI case. Prosecutors may use the results to argue that a driver had too much alcohol in their system or was under the influence of drugs. But a blood test is only useful if the state can show that the correct sample was collected, handled, and tested.
Every blood sample passes through several steps before a laboratory reports the results. If the sample is mislabeled, improperly stored, or transferred without proper documentation, questions may arise about whether the results can be trusted.
A broken chain of custody can sometimes lead to blood test evidence being excluded from court. However, not every mistake is serious enough to have that effect, and the outcome depends on what went wrong.
How Chain of Custody Works in a Georgia DUI Blood Test
Chain of custody is the documented history of physical evidence from the moment it is collected until it is presented in court. In a DUI case, this includes the people who handled the blood sample, where it was stored, and how it reached the laboratory.
A blood sample may pass through the hands of a medical professional, police officer, evidence technician, courier, and laboratory analyst. Each step should provide enough information to establish that the sample remained identifiable and was not improperly substituted or altered.
The purpose is to connect the laboratory’s reported blood alcohol concentration (BAC) or drug findings to the blood actually taken from the driver. Without that connection, even a detailed toxicology report may raise questions about the evidence.
The Evidence Trail From Collection to Testing
A typical DUI blood sample may go through several stages:
- A qualified person collects blood from the driver.
- The collection tubes are labeled and secured.
- Law enforcement receives and stores the sample.
- The sample is transported to a forensic laboratory.
- Laboratory staff inspect and document its arrival.
- An analyst performs the chemical testing.
- Any remaining blood is stored or handled according to applicable procedures.
Records from these stages help establish who had custody of the sample and whether its identity was maintained. A missing entry does not always invalidate the test, but an unexplained gap may become important when other records do not match.
Common Chain-of-Custody Problems With DUI Blood Evidence
Problems can happen during collection, transportation, storage, or laboratory testing. Some involve simple documentation mistakes, while others raise serious concerns about whether the laboratory tested the correct blood.
The effect of an error depends on its nature and the available evidence. A misspelled name may be explained by other identifying information, but conflicting sample numbers or evidence showing the wrong person’s blood was tested can create a much larger problem.
Mistakes During the Blood Draw
Georgia law regulates who may collect blood for chemical testing requested by law enforcement. Under O.C.G.A. § 40-6-392, authorized individuals include certain medical professionals and other qualified personnel.
Problems may arise if the person collecting the blood was not legally qualified, the collection time was recorded incorrectly, or the sample was not properly identified. A tube with missing or conflicting identifying information can make it harder to establish whose blood was collected.
The blood draw itself may also raise separate concerns about collection procedures. For example, improper equipment or collection methods may affect sample quality, even when the chain-of-custody paperwork is complete.
Broken Seals and Improper Storage
Blood samples are typically sealed and packaged to protect them from contamination, leakage, or unauthorized access. Evidence records may identify where the sample was stored and who had access to it.
A broken seal, missing storage entry, or unexplained change in packaging may raise questions about the sample’s condition. However, a damaged seal does not automatically prove that someone tampered with the blood.
Storage conditions may also affect sample reliability. Depending on the testing method and circumstances, improper preservation, unsuitable containers, or delays may raise scientific questions about the results. These issues must be evaluated using the actual collection and laboratory records rather than assuming every delay makes a test inaccurate.
Missing Transportation and Transfer Records
After collection, blood evidence may be transported from a hospital or police department to a crime laboratory. The sample may pass between several people before testing begins.
Transfer records can help establish when the blood changed hands, who received it, and whether the packaging remained secure. Missing signatures, conflicting dates, or unexplained gaps may weaken the evidence trail.
For example, a police report might identify one evidence number while the laboratory intake record lists another. If the discrepancy cannot be explained, the defense may question whether the laboratory received the correct specimen.
Laboratory Intake and Testing Errors
When a blood sample arrives at a forensic laboratory, staff generally document its condition and identifying information. The laboratory may assign a tracking number, inspect packaging, and record where the specimen is stored.
Problems can arise when laboratory records conflict with police documentation. Differences in tube counts, labels, seals, or receipt dates may require further investigation.
The laboratory’s actual testing procedures also matter. Analyst worksheets, instrument records, calibration information, and quality-control results may help determine whether the reported BAC or drug findings are reliable.
Chain-of-custody problems and testing errors are related but different issues. A laboratory might use a reliable testing method on the wrong specimen, or it might correctly identify a sample but perform the analysis improperly. Either situation may create grounds to challenge the evidence.
Georgia’s Rules for Admitting DUI Blood Test Evidence
Georgia courts do not require prosecutors to prove that every possible mistake or act of tampering was impossible. Instead, the state generally must establish with reasonable certainty that the blood tested was the same blood collected and that its identity and integrity were sufficiently protected.
Blood is considered fungible evidence because one person’s sample cannot ordinarily be identified simply by looking at it. That makes records of collection, labeling, storage, and testing particularly important.
Georgia courts have addressed these issues in several decisions. In Buffington v. State, the court explained the reasonable-certainty standard for establishing a chain of custody. In Swanson v. State, discrepancies involving packaging and handling did not automatically require exclusion because the evidence was otherwise sufficiently identified.
Other decisions, including McElwee v. State, show why serious uncertainty about whose blood was actually tested can matter. Cases such as Self v. State and Schlanger v. State also illustrate how detailed collection, storage, and laboratory records can support the admission of blood evidence.
Admissibility Versus the Weight of the Evidence
A chain-of-custody challenge can affect a DUI case in two different ways.
Admissibility concerns whether the judge allows the blood test evidence to be presented at trial. If prosecutors cannot establish a sufficiently reliable connection between the collected blood and the tested specimen, the defense may argue that the results should be excluded.
Evidentiary weight concerns how much the judge or jury should trust evidence that has already been admitted. A minor paperwork inconsistency may not prevent the results from being presented, but it can still be used to question their reliability.
The difference matters because a broken chain of custody does not automatically mean a blood test will be thrown out. Courts consider the seriousness of the problem and whether other evidence explains the discrepancy.
How a Broken Chain of Custody Can Affect DUI Charges
When a blood test provides the main evidence of intoxication, successfully challenging its admissibility can significantly weaken the prosecution’s case. Without the result, prosecutors may have a harder time proving that a driver’s BAC exceeded Georgia’s legal limit.
However, losing a blood test does not automatically mean the DUI charge will be dismissed. Prosecutors may still rely on officer observations, driving behavior, field sobriety evidence, statements, or other admissible evidence.
Georgia also allows DUI charges based on impairment, even when the prosecution does not rely on a specific BAC result. Whether the remaining evidence is sufficient depends on the facts and the particular charges.
A serious evidence problem may affect plea negotiations, support a request to exclude the test, or create reasonable doubt at trial. In some cases, the prosecution may reduce or dismiss charges, but those outcomes are never guaranteed.
Independent Blood Testing and Evidence Preservation
A person accused of DUI may have questions about whether the original laboratory results are accurate. Independent testing of a remaining blood sample may provide additional information about the specimen and the reported findings.
Georgia’s chemical testing law recognizes certain rights involving independent testing. The circumstances of the arrest, the person’s request, and the availability of a qualified testing provider can affect how those rights apply.
If a sample remains available, an independent laboratory may be able to examine it using appropriate methods. However, not every case involves enough remaining blood for additional analysis, and testing may consume some or all of the specimen.
Preservation is also important because blood evidence may be stored, transferred, or eventually disposed of under applicable procedures. Promptly identifying what remains available can help determine whether additional examination is possible.
Records Used to Investigate a DUI Blood Test
Reviewing only the final toxicology report may not reveal what happened to the sample before testing. A chain-of-custody investigation often requires comparing records from several different sources.
Important evidence may include:
- Blood collection forms identifying the person who drew the sample.
- Police reports and body-camera footage from the collection process.
- Evidence logs showing storage locations and transfers.
- Transportation records documenting delivery to the laboratory.
- Laboratory intake records describing the sample’s condition.
- Analyst worksheets, instrument data, and quality-control records.
- Records showing how the remaining sample was stored or handled.
These documents can help identify conflicting dates, unexplained transfers, missing labels, or inconsistencies between police and laboratory records. They may also show that an apparent problem has a reasonable explanation.
A thorough review looks at the entire process rather than relying on one missing signature or a single difference in paperwork. The goal is to determine whether the evidence reliably connects the reported result to the blood collected from the driver.
Frequently Asked Questions
Can a DUI Blood Test Be Thrown Out for a Broken Chain of Custody?
Yes, a serious chain-of-custody problem may support excluding blood test evidence in a Georgia DUI case. However, the defense generally must identify a meaningful issue with the sample’s identity or integrity rather than relying on speculation. Minor documentation mistakes may affect the weight of the evidence without making the results inadmissible.
Does a Missing Signature Make a DUI Blood Test Invalid?
Not necessarily. A missing signature may create a gap in the documentation, but other records or testimony may establish who handled the blood sample. Courts consider the entire evidence trail, so a missing signature alone does not guarantee that the test results will be excluded.
Can Improper Blood Storage Change BAC Test Results?
Improper collection or storage conditions may raise concerns about sample quality and testing reliability. Factors such as contamination, preservation methods, container condition, and delays may need scientific review. Whether a particular problem affected the reported BAC depends on the circumstances and the laboratory evidence.
Can I Request an Independent Test of My DUI Blood Sample?
Georgia law provides certain rights involving independent chemical testing, but the rules depend on the circumstances and timing of the request. If blood remains available after the original analysis, additional testing may also be considered as part of the defense investigation. An independent test is not guaranteed to produce a different result, but it may help evaluate the original findings.
Will My Georgia DUI Case Be Dismissed If the Blood Test Is Excluded?
Not automatically. Even without blood test results, prosecutors may use other evidence to argue that a driver was impaired. However, excluding a significant piece of scientific evidence can change the strength of the case and may affect the available defense strategies or possible outcomes.
Challenge Questionable DUI Blood Test Evidence With Jarrett Maillet J.D., PC
A DUI blood test should not be accepted without examining how the sample was collected, handled, and analyzed. Missing records, conflicting information, or improper procedures may raise questions about whether the results can be trusted. Jarrett Maillet J.D., PC, represents people facing DUI charges in Savannah and throughout the surrounding Georgia communities. If you have concerns about blood test evidence in your case, call 912-713-3426 or contact our firm online to discuss your defense options.
