The night you were arrested, the blood draw probably felt like the end of the story. The nurse tied the tourniquet, filled the vials, the officer sealed everything up, and you were told the lab result would “prove” exactly how much alcohol was in your system. Looking at a high number on that report can feel like the case is already lost.
What almost no one explains is how many steps sit between that needle in your arm and the printout the prosecutor waves around in court. Your blood does not go straight from your vein to a machine and then to a judge. It moves through people, rooms, vehicles, refrigerators, and finally a lab bench, and every one of those steps has to be documented and handled correctly to create reliable, admissible evidence.
I have handled thousands of criminal cases across Arapahoe County and other Colorado courts, and in every DUI blood case I personally go through the chain of custody and lab records line by line. I do not hand that task off to staff because subtle problems in that paper trail can turn what looks like devastating blood alcohol evidence into something a judge questions or a jury doubts. In this article, I want to show you how that happens and why it matters even more if you have prior DUIs.
Call (720) 809-8262 to set up a free, confidential case evaluation to discuss your DUI blood test in Arapahoe County.
Why Chain Of Custody Can Make Or Break A DUI Blood Test
Chain of custody is just a formal way of describing the story of your blood sample. It is the written record that shows who had the sample, when they had it, where it was, and what was done with it from the moment it left your arm until it shows up in an Arapahoe County courtroom. Courts rely on that story to decide whether the vial tested by the lab is the same one taken from you and whether anything happened along the way that could have changed it.
For the prosecution, the chain of custody is part of the foundation they must lay before a judge will even consider letting the blood test into evidence. They typically present forms and logs that show the officer, the nurse, the evidence technician, the courier, and the lab all handled the sample in a continuous, secure way. If the record is thin, inconsistent, or plainly wrong, that foundation starts to crack, and it becomes harder for them to claim the number on the page is reliable.
Many people assume that a blood test is like a calculator answer, fixed and unquestionable. In reality, a blood test is more like a photograph stored on a fragile memory card. If you cannot prove who had the card, how it was stored, and that it was not swapped or damaged, the picture becomes less trustworthy. In DUI cases, that means a judge can decide the chain of custody is too weak and keep the result out entirely, or at least allow the defense to use the problems to attack the weight of the evidence in front of a jury.
How Your DUI Blood Sample Moves From Your Arm To The Lab
To understand why chain of custody matters, it helps to see what is supposed to happen in a typical Colorado DUI blood case. After a traffic stop in Arapahoe County, if an officer arrests you on suspicion of driving under the influence and chooses a blood test, they either obtain your consent or secure a warrant for a blood draw. You are usually taken to a hospital or a blood draw station where trained medical staff perform the draw.
During the draw, the nurse or phlebotomist uses special vials, often gray top tubes that contain preservatives and anticoagulants. Those chemicals help stabilize the sample and prevent clotting and fermentation, but only if the tubes are handled properly. The staff member is supposed to label each vial with your identifying information, the date and time, and sometimes the name or badge number of the officer. The vials are then placed into a blood kit that is sealed, typically with tamper evident tape or packaging.
Once the kit is sealed, it becomes evidence in your DUI case. The officer is responsible for transporting that sealed blood kit from the hospital or draw station to a secured evidence area, usually at the police department or sheriff’s office. When the officer places it into an evidence locker or hands it over to an evidence technician, that transfer should be documented with dates, times, and signatures. This is one of the first places the chain of custody is created on paper.
From there, the sample does not just sit until trial. It is typically shipped or delivered to a state or certified laboratory for analysis. At the lab, staff receive the sealed kit, inspect it, and then accession the sample, which means they log it into their system, assign it a lab number, and record key details like when it arrived and who accepted it. The vials are usually stored, often in a refrigerated area, until they are analyzed.
Where Chain Of Custody Breaks Most Often In Arapahoe County
When I review DUI blood cases from Arapahoe County, I see similar weak spots crop up repeatedly. One common problem is incomplete or sloppy paperwork at the police level. A chain of custody form might show an officer placing a kit into an evidence locker, but there is no recorded time, or the date appears to be before the arrest even happened. Sometimes the form lists a transfer from an officer to an evidence technician, but there is no signature for the technician at all.
Another vulnerable point is the period between the blood draw and the sample reaching a secure, temperature controlled storage location. Officers working long, busy shifts may leave kits in patrol cars longer than they should before logging them in. The paperwork might simply say “submitted to evidence” with no detail about whether the kit sat in a warm vehicle for hours. While these human shortcuts are understandable from an operational standpoint, they can have real consequences for the integrity of the sample.
I also see discrepancies when the evidence moves from local law enforcement to the lab. The police record might show a kit shipped on a certain date, but the lab’s intake log shows it arriving much later, with no explanation for the gap. In other situations, the name or case number on the lab intake record does not match the information on the police forms exactly, raising questions about whether the correct sample was associated with the correct case.
On the lab side, problems can appear when intake records and analysis reports do not line up cleanly. For example, a sample may be logged in under one case number and then reported out under another, or the storage conditions noted in one part of the record do not match those recorded in another. These issues do not automatically prove tampering or mix up, but they open the door for serious questions about how carefully the sample was tracked.
How Chain Of Custody Errors Undermine Blood Alcohol Numbers
Chain of custody errors are not just technicalities. They can affect the science behind your blood alcohol number. Blood is a biological sample that can change over time. If a vial is left unrefrigerated longer than protocols anticipate, or if the preservative in the tube is compromised, fermentation can occur and produce alcohol inside the sample itself. That means the number the lab reports may be higher than what was in your bloodstream at the time of the draw.
Improper handling can also lead to degradation of the sample, which might affect how the lab’s instruments measure alcohol or other compounds. When the documentation shows unusual delays, conflicting storage notes, or unexplained gaps in possession, it becomes much harder for the prosecution to claim the conditions were ideal and the result is beyond question. Those same records can support opinions from physicians or toxicology professionals about whether the conditions described could have altered the result in your case.
Mix ups are another real risk in settings where many blood kits are handled together. If labels are smudged, partially completed, or inconsistent, or if two kits from different cases travel together without precise logging, the possibility of switching vials cannot be dismissed. Courts take the risk of misidentification seriously because the whole point of the chain of custody is to assure everyone that the sample tested actually came from the person on trial.
Legally, judges and juries respond to chain of custody problems in different ways depending on how serious they are. If the documentation is so weak that there is no reasonable assurance the sample was preserved and handled properly, a judge can decide that the prosecution has not met its burden to lay a foundation and exclude the blood test result entirely. In other situations, the judge may allow the result into evidence but recognize that gaps in the chain go to the weight of the evidence, not its admissibility.
Why Chain Of Custody Matters Even More If You Have Prior DUIs
If you have prior DUI convictions, the stakes in your current case are far higher than they were the first time. Prior DUIs can lead to enhanced penalties, including longer potential jail time, steeper fines, and more severe license consequences. Prosecutors and judges in Arapahoe County look closely at a defendant’s record when they make charging and sentencing decisions, and a high blood alcohol number tends to make them less sympathetic.
Because of that, prosecutors may assume that someone with priors will quickly accept a plea if the BAC looks bad on paper. The blood test becomes the backbone of their case and a major source of leverage in negotiations. If that test is treated as beyond question, it becomes very hard to argue for meaningful charge reductions or alternative sentencing options.
A detailed chain of custody review can change that dynamic. When I can point to specific gaps or inconsistencies in how your sample was handled and documented, it forces the prosecution to confront the weaknesses in their evidence. That might mean they have to call additional witnesses, produce more records, or face the risk that a judge or jury will see the same problems I do. In many cases, that pressure can open the door to plea offers that would not be on the table if the blood test appeared airtight.
Even if you have priors, you are entitled to have every piece of evidence in your case examined with the same scrutiny as anyone else. I do not assume that a prior record means the current blood test is automatically correct or that the chain of custody was handled perfectly. I have found that some of the most serious documentation issues show up in cases where everyone involved assumed the defendant would plead out quickly because of their history.
How I Investigate Chain Of Custody Problems In DUI Blood Cases
In every DUI blood case I take, I start by gathering far more than just the final lab report. I obtain available police reports, blood draw forms, evidence submission logs, and lab documentation. I want to see every place your name or case number appears and every signature, date, and time associated with your blood sample. That is the only way to tell whether the chain of custody is complete or full of holes.
Once I have those documents, I go through them line by line myself. I compare the time the officer says you were arrested to the time recorded for the blood draw. I look at when the kit was logged into evidence and when the lab says it arrived. I check that the laboratory accession number matches across all records and that the person who claims to have received the kit actually signed for it. When I find entries that do not line up, I flag them immediately.
Sometimes the paperwork raises questions that call for more digging. In those situations, I may bring in private investigators to pull additional records from law enforcement or the lab, or to identify and locate witnesses who handled the evidence along the way. If there are questions about how a particular delay or storage condition might affect the sample, I consult with physicians or other qualified professionals who can look at the records and provide informed opinions.
I take this approach because I have seen too many cases where a quick or superficial review missed critical chain of custody problems. When a lawyer relies only on the summary lab report, they never see that the sample sat unlogged for an unusual amount of time, or that two different people claimed to have custody at the same moment. By handling this analysis personally instead of delegating it to a paralegal or associate, I make sure those details get the attention they deserve.
What You Can Do Now If A DUI Blood Test Is Hanging Over You
Seeing a high blood alcohol number on a report can make you feel like your options have already disappeared. That feeling is even stronger if you have prior DUIs and know the penalties can be severe. Before you decide that your case is hopeless, it makes sense to find out how strong that blood test really is and whether the chain of custody holds up under close inspection.
A good first step is to gather any paperwork you already have, such as your summons, any copies of reports, and any documents that mention the blood test or lab. It also helps to write down everything you remember about the night of the arrest and the blood draw itself. Details like how long you waited at the hospital, who handled the vials, and what you saw the officer do with the kit can be useful when I compare your memory to the official records.
When you schedule a free initial consultation with my office, I can review what you bring and explain what additional records I would request if we work together. We can talk through the path your blood sample likely took in your case, where chain of custody issues often show up in Arapahoe County, and what it would mean for your defense if we find those issues in your file. I will also be honest about cases where the chain appears solid so you can make informed decisions about your next steps.
Talk With A DUI Defense Attorney About Your Blood Test & Chain Of Custody
A DUI blood test is not just a number printed on a page. It is the endpoint of a long chain of handling, storage, and documentation, and every weak link in that chain is a potential opening in your defense. Once you understand how fragile that process can be, it becomes clear that you should not make life changing decisions about pleas or trials without knowing whether the State’s evidence can withstand serious scrutiny.
I personally review DUI blood test and chain of custody records for clients across Arapahoe County from my offices in Denver and Greenwood Village, and I use what I find to push back against the idea that a lab result ends the conversation. If you are facing a DUI charge, especially with prior DUIs on your record, I invite you to schedule a free consultation so we can look at your blood test paperwork together and talk about your options.
Call (720) 809-8262 to set up a free, confidential case evaluation to discuss your DUI blood test in Arapahoe County.