You probably remember the moment someone told you your blood alcohol level, like it was the final word on your case. That single number can feel like a brick wall, especially if it is higher than you ever expected. In Colorado, where DUI enforcement is aggressive, it is easy to assume that a “scientific” blood test ends the conversation about guilt.
The reality is very different. That blood alcohol number is not created in a vacuum. It is the end of a long chain of human actions, choices, and record keeping that begins at the moment of the blood draw and continues through storage, transport, analysis, and court. At every step, there are opportunities for mistakes, shortcuts, or gaps in documentation that can directly affect whether the result is reliable enough to use against you.
At The Orr Law Firm, our practice in Denver focuses on defending DUI and criminal charges, and a big part of that work involves taking apart blood test evidence piece by piece. We regularly obtain and review chain of custody logs, lab records, and police reports in Colorado DUI cases, looking for process failures that are invisible on the surface.
In this article, we explain how blood test chain of custody really works and how errors in that chain can sabotage accuracy and create real defenses in your case.
What Blood Test Chain of Custody Really Means in a DUI Case
Chain of custody is a phrase you might see in your paperwork or hear in court, but it is often misunderstood. In a DUI blood case, chain of custody refers to the documented trail showing who had your blood sample, where it was, how it was stored, and what was done with it from the moment it was drawn until it was analyzed and stored as evidence. Each handoff should include dates, times, names, and signatures so that a judge can see there are no unexplained gaps.
Prosecutors rely on this documentation to ask a Colorado court to admit a blood test result. They must show that the sample tested at the lab is the same one drawn from you, that it was not tampered with, contaminated, or mixed up, and that it was kept under conditions that preserved its integrity. If the blood test chain of custody is thin, sloppy, or incomplete, the court must decide whether the result is trustworthy or whether its evidentiary value is diminished.
Chain of custody differs from equipment error. While a breath machine calibration problem is primarily mechanical, blood tests involve both analytical accuracy and evidence handling. Even a perfectly working lab instrument cannot compensate for breaks in the chain of custody. At The Orr Law Firm, we examine both sides to identify weaknesses that may undermine a blood test result.
How a DUI Blood Sample Should Be Handled in Colorado
To identify where problems arise, it helps to understand how a proper blood test chain of custody works in Colorado DUI cases. A blood sample is drawn by a qualified professional at a hospital, clinic, or law enforcement facility.
Before the draw:
- The site should be cleaned with a non-alcohol based swab.
- Correct blood tubes must be prepared.
- The professional verifies your identity and case information.
After the draw, the blood is placed into vials containing preservatives and anticoagulants, labeled with your name, date, time, initials of the collector, and case or agency number. The vials are then placed in a sealed blood kit, often secured with tamper-evident tape and accompanied by an evidence or chain of custody form.
From there, the kit should be stored under proper conditions, typically in a locked, refrigerated evidence room at a police department or sheriff’s office. Each transfer, from storage to lab transport, should be documented with the responsible officer’s signature and timestamp.
Upon arrival at the lab:
- The kit is logged in, seals are checked, and the case number is verified.
- The sample is stored under refrigeration until testing.
- An analyst runs the sample through approved methods, documenting controls, standards, and results.
All of these steps generate paperwork: police reports, evidence sheets, chain of custody logs, and lab intake forms. Attorneys experienced in Denver DUI defense know what these documents should look like and can spot missing or out-of-sequence records.
Where Chain of Custody Breaks Down in Real Denver DUI Cases
In practice, chain of custody errors often occur due to human error or shortcuts.
Common issues include:
- Draw stage mistakes: vials labeled with only last names, illegible handwriting, missing signatures, or mismatched times.
- Storage and sealing problems: broken or re-taped seals, incomplete refrigeration logs, or unclear access records.
- Transport gaps: kits held in patrol cars without documentation, batch transport entries without individual tracking.
- Lab intake errors: incorrect case numbers, missing handoff records, illegible initials, and unclear separation of duties.
Even small documentation gaps can have significant legal implications. At The Orr Law Firm, our Denver DUI defense lawyers focus on identifying these weaknesses to challenge the reliability of blood test results.
How Chain of Custody Errors Can Distort Blood Test Accuracy
Errors in chain of custody do more than create paperwork inconsistencies—they can scientifically alter your blood sample.
Key risks include:
- Time and temperature effects: samples left in warm cars or unrefrigerated evidence rooms can allow microorganisms to grow, fermenting blood and increasing alcohol readings.
- Preservative issues: incorrect tube types, improper blood-to-preservative ratios, or inadequate mixing can reduce the effectiveness of anticoagulants and preservatives.
- Contamination: alcohol-based swabs, unclean gloves, or contact with surfaces can introduce foreign substances.
- Whole blood vs. serum: different components can yield varying alcohol concentrations, and misinterpretation of these results can affect legal assumptions.
Our Denver DUI defense lawyers routinely review the underlying lab data, including batch runs, controls, and internal records, tying scientific concerns to chain of custody weaknesses to challenge the accuracy of results.
When Chain of Custody Problems Can Help Your DUI Defense
Chain of custody errors are legally significant because Colorado courts require the prosecution to demonstrate that a blood sample was handled in a way that ensures its reliability.
Potential legal outcomes include:
- Suppression of evidence: courts may exclude blood test results if chain of custody cannot be reliably established.
- Reduced evidentiary weight: judges and juries may view results as less reliable if documentation is sloppy.
- Negotiation leverage: documented weaknesses can lead to reduced charges or better plea agreements.
Our attorneys carefully distinguish between minor clerical errors and substantive chain of custody failures. In Denver DUI cases, credibility and courtroom experience allow us to cross-examine officers, phlebotomists, and lab analysts effectively, making chain of custody a tangible part of your defense strategy.
Common Myths About DUI Blood Tests and Chain of Custody
Clients often come with misconceptions about blood tests and chain of custody in blood tests:
- Myth 1: Police and labs always follow protocol perfectly. Reality: small but important errors often remain buried unless examined by a defense lawyer.
- Myth 2: Chain of custody issues are technicalities unrelated to actual intoxication. Reality: the law depends on trustworthy evidence; mishandling can invalidate results.
- Myth 3: Only dramatic events matter, like lost samples. Reality: a pattern of smaller errors—mismatched times, missing initials, disturbed seals—can collectively undermine reliability.
Judges notice inconsistencies, and our Denver DUI defense lawyers are skilled at highlighting them respectfully and factually.
How We Scrutinize Blood Test Chain Of Custody In Denver DUI Cases
When we take on a DUI blood case, we do not stop at the one-page lab report or the number written in a police narrative. We request and review the complete set of available records, which typically includes chain of custody logs, evidence sheets, officer reports, and lab intake and analysis documents. We compare how each of these pieces describes the handling of your sample and look for points where the story changes or where the documentation is missing or vague.
Part of that review involves lining up times, dates, and locations. We ask whether the time of draw listed by the person who took your blood matches the time in the officer’s report and the time marked on the evidence form. We check when the kit was logged into evidence at the agency, how long it remained there, and when it was checked out for transport. If the records show your kit left a station at a certain time and the lab claims to have received it earlier than that, we dig into why those entries do not match.
We also look closely at who handled your sample. If there are initials on a log with no printed names, we ask for clarification. If the same person appears to have received, stored, and transported multiple kits without clear separation of duties, we consider how that might affect the risk of mix-ups. At the lab, we examine whether the seals were documented as intact, whether the analyst followed standard procedures, and whether the internal lab records support the story told on the final report.
Because we build DUI defenses case by case, we do not assume every chain of custody is flawed and we do not assume every problem is fatal. We treat each file as its own puzzle. In some cases, the chain is strong and we focus more on other issues, such as driving behavior or constitutional questions about the stop or arrest. In other cases, the chain is riddled with issues, and we make those problems a central part of our strategy in motions, negotiations, and at trial when necessary.
What You Can Do Now About Your DUI Blood Test
If your Colorado DUI case involves a blood test, you don’t have to accept the reported number as definitive. A key first step is to gather all relevant paperwork, including your citation, police reports, and lab results, and bring them to a qualified defense firm. This allows attorneys to spot potential issues, request additional records, and begin building a strategy based on a full understanding of how your blood sample was handled.
Timing is critical because Colorado courts move quickly on DUI cases, and there are strict deadlines for filing motions, such as motions to suppress evidence. Early review of your blood test documentation and chain of custody records increases the options for challenging the evidence or leveraging weaknesses during negotiations. A skilled defense team can help protect your rights, driving privileges, and future by thoroughly examining the chain of custody and lab procedures, ensuring every detail is scrutinized for potential defenses.
If you are concerned about how your blood sample was handled, we invite you to reach out online or call (303) 747-4247 so we can talk through your specific situation and review the records together.