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  • Writer's pictureJustin Sparks

How Do I Challenge a DUI Blood Test? A Comprehensive Guide

A DUI can have more far-reaching consequences than one can imagine, and it can be embarrassing and affect a person's career, social life, and more. Many people don't realize that there may be discrepancies in a DUI blood test result that can help them avoid a conviction.


Dismissing DUI charges or the blood test results in court can help prove the defendant's innocence, allowing them to return to their daily lives. However, fighting DUI charges or dismissing blood test results can be challenging, which is why it is crucial to reach out to an experienced criminal defense attorney.


The criminal defense attorneys at Sparks Law Firm have over 100 years of combined experience helping their clients in Fort Worth, Texas, with their criminal cases, including DUI. There are always two experienced attorneys working on every single client, ensuring that nothing slips through the cracks and always keeping the clients informed.


Those facing DUI charges must immediately contact the reputable criminal defense attorneys at our DWI law firm for a free consultation on their DUI case.


The Procedure Leading to a DUI Arrest

The Procedure Leading to a DUI Arrest

When law enforcement officers suspect a driver of DUI, they may ask them to pull over and question them about their driving.


During this stage, the officers may require the driver to pass the sobriety test, including asking them to walk in a straight line or monitoring their speech for slurred wordings. If there is doubt that the driver may be under the influence, law enforcement officers have the right to arrest the driver and take them in for further investigation.


After the DUI arrest, the police officers may request the driver for a breath or blood test at the police station or a nearby hospital. The test helps them determine whether the driver's Blood Alcohol Content (BAC) is above the legal limit, which may vary from one state to another.


Challenging the blood test results can be difficult, especially if it comes back with a high score. However, an experienced criminal defense attorney understands that there are many ways to challenge the DUI blood test results legally. It is crucial for drivers who submit a blood alcohol test to discuss their case with an experienced DUI attorney. Sparks Law Firm can also answer questions like, "What are DUI classes like?"


How Do I Challenge a DUI Blood test result in Court?


There are two main ways individuals can challenge DUI blood test results, including the following.


Blood Test Reliability


Although a blood test is more reliable than a breath test, they aren't always foolproof and has led to complications for the prosecutor to prove the blood alcohol test results in court.


When taking blood samples, it is crucial that the healthcare professional drawing the blood handles the samples carefully, as contamination can result in an inaccurate Blood Alcohol Content result.


Lack of care when handling blood samples could lead to fermentation in the blood sample vial, causing the blood alcohol concentration level to rise. When that happens, it can be challenging to determine how much is from the suspect and how much is from the fermentation.


Another major issue that can arise with blood samples is the duration between the suspect driving the car and the blood test samples taken. Alcohol can take time to enter the bloodstream, meaning a person's alcohol level changes by the minute.


If the defendant drank a few drinks and immediately drove their car before being pulled over, the alcohol may not have had enough time to enter the bloodstream. As time passes, the alcohol gets absorbed into the bloodstream causing the defendant's BAC levels to rise. As a result, the defendant's BAC would be lower before getting pulled over than an hour later when they give the blood sample.


In the legal world, this is commonly referred to as the "rising blood alcohol" defense. The defense states that the defendant's BAC was lower than the legal limit at the time of driving but higher at the time of the blood draw.


Illegal Search and Seizure


The Fourth Amendment protects people from unreasonable searches and seizures by the government. A search and seizure without a valid warrant is against the Constitution and considered "unreasonable."


According to the US Supreme Court, drawing blood for a blood test falls under search and seizure, and the law enforcement officer must have the warrant to request a blood sample.


Failure to furnish a warrant before drawing blood is a violation of the person's rights given to them under the US Constitution. However, there are some circumstances when law enforcement does not need a warrant before drawing blood, including when the suspect is unconscious.


If a defendant gets their blood drawn without a proper warrant, their defense attorney can argue in court that the law enforcement violated the defendant's rights and conducted an illegal search and seizure, dismissing the results of the blood tests.


How Can Defense Attorneys Challenge the Blood Test Results in Court?


When representing clients, attorneys at Sparks Law Firm have extensive experience challenging blood test results in court.


Besides using DUI defenses such as "lack of probable cause" or "rising blood alcohol," experienced attorneys at Sparks Law Firm can aggressively challenge the technology, procedure, or testimony to get a plea bargain or a "not guilty" verdict in a jury trial.


Challenge the Technology


Depending on the condition of the equipment used to draw blood, a skilled attorney can challenge the blood test results, as malfunctioning equipment can be a cause for dismissal. If the blood sample was improperly stored or the blood draw did not happen within two hours, it can be grounds for challenging blood test results.


Challenge the Procedure


An experienced attorney at Sparks Law Firm knows that every DUI case is different. They will investigate the circumstances surrounding the arrest and blood draw to find any evidence that they can use to challenge the blood test.


The blood test results are inadmissible if the person who drew the blood was not legally certified to do the job. For example, a certified nurse and doctor can legally draw a blood sample. An uncertified law enforcement officer cannot legally draw blood, and if they do, the attorney can have the test results thrown out of the courtroom.


Another key concern is whether the certified professional taking the blood sample used an alcohol-based product to sterilize the blood draw site. It is the defendant and their attorney's right to ask this question, as using an alcohol-based product can contaminate the blood sample, resulting in a higher BAC.


There may be troubling gaps in the chain of custody. Authorities must ensure that they keep track of the blood sample to avoid any tampering. Police must know who drew the blood, who carried the blood sample to the toxicologist or laboratory, and who was the officer who filed the blood test into evidence.


Any gaps in the chain of custody could be enough for an attorney to argue the basis of the test results and have them thrown out of court.


Challenge the Testimony


Another way the defense can challenge the blood test results is by challenging the officer's testimony. A smart DUI attorney knows how to question the officer's certification and qualifications, explore the officer's history of DUI arrest records to find any suppression of evidence or misinformation and gather the evidence against the officer's testimony.


According to the Denver Post, Gilpin County Judge David Taylor ruled in favor of the defendant, who argued that the breathalyzer used in the county produced false results. During the case, it was found that several regulators responsible for conducting breathalyzer tests provided falsified certificates that attested to the equipment's accuracy. The findings of the case produced reasonable doubt, which resulted in a verdict in favor of the defendant.


If a criminal defense attorney can find a single piece of evidence that contradicts an officer's testimony, it may be enough to dismiss all charges against the defendant.


What Are the Steps to Challenging a DUI Blood Test?

What Are the Steps to Challenging a DUI Blood Test?


Facing DUI charges can lead to dire consequences, especially if the defendant cannot prove that they are innocent. It is crucial for them to follow the steps below to help them challenge the DUI blood test results.


Reach Out to an Experienced DUI Attorney


Handling a DUI case without an experienced criminal defense attorney can completely go south for the defendant, especially if they're not sure what they're doing. It is essential for individuals who submitted to the blood test (willingly/unwillingly) to reach out to an experienced DUI attorney.


A skilled DUI attorney can protect the defendant's rights and help them understand their legal options after discussing the case with them. If the attorney feels that there may be substantial evidence to fight the conviction, they may guide the defendant on the next steps.


Examine the Blood Test Results


The attorney will start by reading the blood test results for information that could tell them more about the DUI arrest, such as the test date, the type of blood testing procedures used, and the blood alcohol level.


After going over the necessary information, the attorney will examine the blood test results to determine any discrepancies, such as whether or not the individual drawing the blood had the required certifications and qualifications, whether there was any lack of care when handling the blood sample, and did the equipment used for the blood draw have any issues.


Investigate and Question Blood Testing Procedures


After examining the test results for discrepancies, the DUI attorney will look at the test logs and investigate the chain of command to determine if the law enforcement officers followed the relevant protocols.


The attorney can also interview the officers involved to gather information and cross-examine them with the testimonies provided.


Bring on Expert Witnesses


Having an expert in forensic science and toxicology can be a deal breaker in a DUI case. An expert witness has the experience and knowledge to provide scientific testimony on the reliability of the testing procedures to measure blood alcohol concentration. They can be an invaluable addition to a DUI case, and a reputable criminal defense attorney has the connections and resources to bring such experts on board.


File the Necessary Legal Motion


Once the attorney finds issues with the blood alcohol testing procedures or the blood alcohol results, they will plan their next step, which in most cases is filing a motion to challenge the evidence presented by the prosecutors.


Present their Case in Court


When the attorney files the necessary legal motion, they must attend the court hearings, which may lead to a trial. During the trial, the prosecutors have the proof of burden to provide evidence that the defendant had a higher BAC level than the state's legal limits.

Each side will start with an opening statement where the prosecutor will talk about the evidence they may use in the DUI case. On the other hand, the attorney will let the jury know if they plan on bringing witnesses or cross-examining the evidence.


The prosecutor will present their evidence, while the attorney will get the opportunity to question the integrity and reliability of the evidence presented in court. Under the court proceedings, the defense can also introduce evidence whereby the attorney can challenge the technology used or the DUI blood testing procedure carried out by law enforcement.


After both sides have presented the argument, the judge will explain the relevant laws to the jury, and they can decide whether or not the defendant is guilty. If the evidence presented by the prosecutor creates reasonable doubt, the defendant is not guilty, and they can leave the courtroom without a conviction.


Schedule a Free Consultation with Experienced Criminal Defense Attorneys in Fort Worth, Texas


Those facing DUI charges or have willingly/unwillingly submitted to a blood test in Fort Worth, Texas, must call (817) 381-7846 for a free consultation with experienced criminal defense attorneys to discuss their case.


The legal team at Sparks Law Firm is extremely proactive, providing unparalleled legal expertise. They treat every client with respect and are passionate about going above and beyond to exonerate them.

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