Blood Testing (BAC Test)

Blood testing is one of the primary chemical-testing methods used in Colorado DUI investigations. Unlike a breath test, which estimates blood alcohol concentration by measuring alcohol in a breath sample, a blood test directly analyzes a sample of the driver’s blood. Depending on the testing requested, the laboratory may measure alcohol concentration, identify drugs or controlled substances, or test for both alcohol and drugs.

Colorado law enforcement officers commonly request blood testing when they suspect a driver is under the influence of drugs, when alcohol and drugs may both be involved, when a breath-testing instrument is unavailable, or when the driver chooses blood testing in an alcohol-related case. Blood samples may also be obtained after serious or fatal crashes when law enforcement has the legal authority required to conduct the test.

Blood evidence can become an important part of a prosecution for driving under the influence, DUI per se, driving while ability impaired, vehicular assault, or vehicular homicide. However, a reported laboratory result does not automatically prove that a person was impaired while driving. The blood draw, labeling, storage, transportation, laboratory analysis, and interpretation of the result must all be carefully examined.

Colorado requires forensic toxicology laboratories that perform alcohol and drug testing to satisfy state certification requirements. These requirements include inspections or accreditation, proficiency testing, and compliance with Colorado Board of Health rules governing alcohol and drug testing.

Denver DUI Blood Test Lawyer

If you were arrested for DUI after submitting to or refusing a blood test, it is important to begin reviewing the evidence as soon as possible. Blood testing may appear highly scientific, but numerous problems can arise between the moment the sample is collected and the moment a laboratory reports a result. An improperly collected, mislabeled, contaminated, poorly stored, or incorrectly analyzed sample may produce unreliable evidence.

A DUI arrest can create two separate legal proceedings. The criminal case is handled through the courts, while the Colorado Division of Motor Vehicles determines what happens to the driver’s license. These proceedings operate independently, meaning a favorable result in one does not automatically resolve the other.

Colorado DUI defense attorney Matthew Martin at The Law Office of Matthew Martin can review the blood draw, laboratory records, police reports, body-camera footage, chain-of-custody documents, and other evidence in your case. Call 303.725.0017 today or fill out our online consultation form to schedule a free consultation.

The Law Office of Matthew Martin represents clients throughout the greater Denver area, including Denver, Boulder, Aurora, Westminster, Louisville, Englewood, Greeley, Parker, and Castle Rock.

Overview of DUI Blood Testing in Denver, Colorado

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How Does DUI Blood Testing Work in Colorado?

A DUI blood test begins with the collection of one or more vials of blood from the driver. The draw is ordinarily performed at a hospital, clinic, jail, law enforcement facility, or another location where a qualified person is available to collect the sample.

The person drawing the blood typically uses a collection kit designed for forensic testing. The kit may contain specially prepared tubes, labels, seals, and paperwork. After the blood is collected, the tubes should be labeled with identifying information, sealed, documented, and transferred for storage and transportation to a certified laboratory.

Once the sample reaches the laboratory, the type of analysis depends on what law enforcement requested. An alcohol test measures the concentration of ethanol in the blood. A drug test may screen for and confirm the presence of marijuana-related compounds, prescription medications, controlled substances, or other drugs that could affect driving.

The laboratory then issues a report identifying the substances detected and, when appropriate, their measured concentrations. Prosecutors may rely on that report in the criminal case, while the DMV may use an alcohol result of 0.08 or higher to begin an administrative license-revocation proceeding.

The accuracy of the result depends on every stage of the process. Proper specimen collection, labeling, storage, packaging, and transportation are necessary to protect the integrity of a sample. Colorado’s public-health guidance emphasizes that samples must be packaged and transported in a manner that preserves their integrity and complies with applicable requirements.

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When Is a Blood Test Used in a Colorado DUI Investigation?

Blood testing may be used in several different types of DUI investigations. The reason for the test often determines what substances the laboratory will look for and how the results may be used.

Suspected Alcohol-Impaired Driving – When an officer has reasonable grounds to believe that a driver is impaired by alcohol, the driver may be asked to complete an evidential breath test or a blood test. A blood test directly measures alcohol in the sample rather than estimating BAC from the driver’s breath. Blood testing may be selected because the driver prefers that method, because an evidential breath instrument is unavailable, or because circumstances make breath testing impractical. For alcohol testing, Colorado DMV guidance recognizes an officer-requested blood test or an evidential Intoxilyzer test as satisfying the post-arrest chemical-testing requirement.

Suspected Drug-Impaired Driving – Blood testing is especially common when an officer suspects impairment by marijuana, prescription medication, illegal drugs, or a combination of substances. Breath-testing instruments do not detect most drugs, so a blood sample is usually more useful in a drug-DUI investigation. An officer may base the request on the driver’s behavior, statements, physical symptoms, possession of drugs or medication, field sobriety performance, or an evaluation conducted by a drug recognition expert. The laboratory may then test the sample for substances that could explain the observed behavior.

Suspected Combined Alcohol and Drug Use – Some DUI investigations involve allegations that a driver consumed both alcohol and drugs. A person may have an alcohol concentration below 0.08 but still face DUI or DWAI allegations based on the combined effects of alcohol, marijuana, prescription medication, or another drug. A blood sample may be tested for both alcohol and controlled substances. Prosecutors may attempt to use the combination of results and officer observations to argue that the substances impaired the person’s ability to drive safely.

A Driver Is Unable to Complete a Breath Test – A blood test may also be used when a driver cannot provide an adequate evidential breath sample. A respiratory condition, physical injury, unconsciousness, or another medical issue may prevent breath testing. Whether law enforcement may obtain the blood sample and whether the person’s conduct constitutes refusal depend on the circumstances. A genuine medical inability to complete a breath test should not automatically be treated the same as an intentional refusal to cooperate.

A Serious or Fatal Collision Occurred – Blood testing frequently becomes an issue after collisions involving serious bodily injury or death. These cases may lead to investigations for DUI, vehicular assault, vehicular homicide, or another serious offense. The occurrence of a crash alone does not eliminate constitutional protections. Law enforcement must still rely on valid consent, Colorado’s applicable testing statutes, a search warrant, or another recognized legal basis for obtaining the sample.

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Colorado’s Express Consent Law and Blood Tests

Colorado’s Express Consent Law provides that a person who drives in the state is considered to have consented to chemical testing when a law enforcement officer has reasonable grounds to believe the person drove under the influence of alcohol, drugs, or both. The law applies to qualifying post-arrest chemical testing and is separate from voluntary roadside screening.

When alcohol is suspected, the required chemical test may involve blood or evidential breath testing. When drugs are suspected, an officer may request a blood test capable of detecting and measuring relevant substances.

A driver’s refusal can result in administrative license consequences even if the criminal charge is later reduced or dismissed. The alleged refusal may also be introduced in the criminal case as evidence of consciousness of guilt.

Express consent does not mean that officers may disregard all constitutional and statutory requirements. Issues may still arise concerning whether the officer had reasonable grounds, whether the driver was lawfully arrested, whether the person was properly advised, whether the requested test was appropriate, and whether the driver actually refused.

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Can Police Force a Blood Draw in Colorado?

A forced or involuntary blood draw raises significant constitutional issues because drawing blood is a search of the person’s body. In many circumstances, officers must obtain a search warrant before taking blood without the driver’s voluntary consent.

A warrant request may be supported by allegations that the officer had probable cause to believe the driver committed DUI or another offense and that the blood would contain evidence of alcohol or drug use. A judge must then determine whether probable cause supports the requested search.

Certain limited exceptions may apply, including circumstances recognized under Colorado law or constitutional search-and-seizure principles. However, the fact that alcohol naturally leaves the bloodstream does not automatically justify every warrantless blood draw. The legality of the draw must be evaluated based on the particular facts.

Colorado law also addresses the admissibility of certain involuntary blood-test evidence in prosecutions involving impaired driving and specified crash-related crimes. Whether the statute applies and whether the draw complied with constitutional requirements are separate questions that may require litigation.

A defense attorney may challenge:

  • Whether probable cause existed;
  • Whether the warrant application contained accurate information;
  • Whether officers exceeded the scope of the warrant;
  • Whether a claimed exception to the warrant requirement applied;
  • Whether the blood was drawn in a medically acceptable manner; or
  • Whether officers complied with Colorado’s testing requirements.

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What Do Blood Alcohol Test Results Mean?

For most drivers who are at least 21 years old, a blood alcohol concentration of 0.08 or higher may support a DUI per se charge. DUI per se focuses on the measured alcohol concentration rather than requiring the prosecution to prove impairment solely through physical behavior or driving conduct.

A BAC above 0.05 but below 0.08 may support an inference relevant to a DWAI charge. DWAI applies when alcohol, drugs, or a combination of substances affect a person to the slightest degree so that the person is less capable than ordinarily of exercising clear judgment, physical control, or due care while driving.

A result below 0.08 does not guarantee that no charge will be filed. Prosecutors may rely on officer observations, driving behavior, field sobriety exercises, statements, video recordings, and evidence of drug use to pursue DUI or DWAI.

Different standards and consequences may apply to commercial drivers and drivers younger than 21. Colorado also designates a person with a chemical-test BAC of 0.15 or higher as a Persistent Drunk Driver, which can create additional education, treatment, reinstatement, and ignition-interlock consequences.

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What Do Drug Blood Test Results Mean?

A drug blood test may identify one or more controlled substances, prescription medications, or metabolites. Unlike alcohol, however, the presence or concentration of many drugs does not always establish a direct and predictable level of impairment.

Different people can experience the same drug differently based on tolerance, dosage, frequency of use, metabolism, interactions with other substances, and the time between consumption and testing. A laboratory result must therefore be considered together with the driver’s behavior and the circumstances of the investigation.

For marijuana-related cases, a blood test may measure active delta-9 THC. Colorado law permits a fact finder to draw a permissible inference that a driver was under the influence of marijuana when the blood contains at least five nanograms of delta-9 THC per milliliter. This is not the same as an automatic conviction or an absolute per se limit. The defense may introduce evidence showing that the driver was not impaired despite the reported concentration.

A positive result for a prescription medication likewise does not automatically establish DUI. A person may lawfully possess and use a prescribed drug but can still be charged if prosecutors allege that it impaired the person’s ability to drive. The central question is not merely whether the drug was present, but whether the prosecution can prove the required degree of impairment.

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What Factors Impact DUI Blood Test Accuracy?

Blood testing can be more direct than breath testing, but it is not immune from error. A laboratory report is only as reliable as the collection, storage, transportation, testing, and interpretation that produced it.

Improper Blood Collection – The blood draw should be performed by an authorized and properly trained person using appropriate procedures. Problems can arise if the wrong equipment is used, the collection site is not properly prepared, the tubes are underfilled, or the sample is handled incorrectly. The defense may examine who performed the draw, the person’s qualifications, the collection notes, the condition of the kit, and whether the procedure complied with applicable standards.

Use of an Alcohol-Based Skin Preparation – A nonalcoholic antiseptic is generally used when blood is being collected for forensic alcohol analysis. If an alcohol-based preparation was used near the puncture site, the defense may investigate whether it could have contaminated the sample. The mere use of an alcohol-containing product does not prove that the result was wrong, but it can create an issue requiring review of the collection records and testimony from the person who performed the draw.

Incorrect Tubes or Preservatives – Forensic blood-collection tubes ordinarily contain substances intended to preserve the sample and reduce changes before testing. If the wrong tube was used, the tube was expired, the additives were missing, or the blood and preservatives were not properly mixed, questions may arise about sample integrity. The defense may inspect photographs, kit records, tube lot numbers, expiration dates, and laboratory documentation to determine whether the collection materials were appropriate.

Fermentation or Sample Decomposition – Microorganisms can sometimes produce alcohol in a poorly preserved biological sample. Proper preservatives, refrigeration, storage, and laboratory practices are intended to reduce this risk. If the sample was exposed to heat, left unrefrigerated, improperly sealed, or stored for an extended period, the defense may investigate whether fermentation or decomposition affected the reported alcohol concentration.

Improper Storage or Transportation – Blood samples must be stored and transported under conditions that protect their integrity. Delays, excessive temperatures, broken seals, leaking tubes, or inappropriate packaging may compromise the evidence. Colorado’s laboratory guidance stresses the importance of proper labeling, packaging, and transportation. A documented departure from those procedures may support a challenge to the reliability of the test.

Laboratory Contamination – Contamination can occur during sample preparation, testing, or handling. Laboratories should use quality-control measures to detect contamination and ensure that instruments do not carry material from one sample into another. A defense attorney may examine blank samples, control results, batch records, instrument maintenance, and testing sequences to determine whether contamination could have affected the defendant’s result.

Instrument Calibration or Maintenance Problems – Laboratory instruments must be properly maintained and calibrated. Failed controls, unresolved error messages, repairs, or calibration problems may undermine confidence in the reported result. The laboratory’s quality-assurance documents can show whether the instrument performed within acceptable limits before, during, and after the analysis.

Sample Mislabeling or Mix-Ups – The prosecution must establish that the blood tested by the laboratory came from the accused driver. Incorrect labels, incomplete identifying information, inconsistent numbers, or unexplained discrepancies can raise the possibility of a sample mix-up. A defense attorney can compare the collection documents, seals, accession records, testing worksheets, and final report to identify inconsistencies.

Measurement Uncertainty – No scientific measurement is perfectly exact. Laboratories generally recognize a range of uncertainty around a reported numerical result. Measurement uncertainty may be particularly important when a reported alcohol or drug concentration is close to a legally significant threshold. The defense may argue that the prosecution should not present the reported number as more precise than the science permits.

Timing of the Blood Draw – A blood test measures the concentration present when the sample was taken, not necessarily the concentration while the person was driving. Alcohol levels may still be rising after the person stops driving, while drugs may be absorbed, distributed, and eliminated in different ways. A delay between driving and collection can therefore affect how the result should be interpreted. The prosecution may use retrograde-extrapolation testimony to estimate an earlier BAC, but that analysis depends on assumptions about drinking times, absorption, food consumption, and elimination.

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How Long Does It Take to Receive Blood Test Results?

Blood-test results are usually not available immediately. The sample must be transported to a certified laboratory, documented, tested, reviewed, and reported. Drug testing may take longer than alcohol testing because the laboratory may need to screen for several substances and conduct separate confirmation testing.

While awaiting the result, the criminal case may still proceed through initial court appearances and pretrial stages. The driver’s license process also differs from a breath-test case because the DMV may not begin a per se action until the blood result is received and notice is issued.

Colorado DMV guidance states that a motor vehicle hearing must generally be requested within seven days after receiving the blood-test results. By comparison, a hearing concerning a refusal must generally be requested within seven days of the arrest.

Because the deadline is short, a person who receives a notice based on a blood result should review it immediately rather than waiting for the next criminal-court date.

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Penalties for Refusing a Blood Test in Colorado

Refusing a lawfully requested blood test can result in administrative penalties under Colorado’s Express Consent Law. These consequences are separate from any sentence imposed in the criminal DUI case.

The general refusal revocation periods are:

  • First refusal: One-year driver’s license revocation
  • Second refusal: Two-year driver’s license revocation
  • Third or subsequent refusal: Three-year driver’s license revocation

A refusal also results in a Persistent Drunk Driver designation. That designation may require Level II alcohol and drug education and treatment, proof of insurance, payment of reinstatement fees, and an ignition-interlock-restricted license.

Eligible Colorado residents who were at least 21 at the time of the violation may be able to pursue early reinstatement after serving two months of a refusal revocation and satisfying the other applicable requirements. Eligibility depends on the person’s record and circumstances and should be confirmed directly with the DMV.

A refusal may also be introduced in the criminal case. Prosecutors may argue that the driver refused because the person believed the test would reveal alcohol or drugs. The defense may offer a different explanation, including confusion, fear of needles, inadequate advisement, a language barrier, a medical condition, or an attempt to cooperate with another valid form of testing.

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Can a Driver Refuse a Blood Test but Request a Breath Test?

In an alcohol-only investigation, the availability of a choice between blood and breath can depend on the circumstances and the requirements of Colorado’s Express Consent Law. If both tests are reasonably available, the driver’s requested method may become important.

When an officer reasonably suspects drugs or a combination of alcohol and drugs, breath testing may not provide the evidence needed to identify the suspected substance. In those circumstances, the officer may request blood testing even though the driver would prefer a breath test.

A driver should not assume that offering to take a different test automatically prevents a refusal finding. The defense must examine exactly what the officer requested, what options were explained, whether the requested test was reasonably available, and how the driver responded.

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Defenses to DUI Blood Test Evidence in Colorado

A blood test may appear persuasive because it produces a numerical laboratory result, but that evidence can be challenged. The appropriate defenses depend on the legality of the stop and arrest, the authority for the blood draw, the integrity of the sample, the laboratory’s procedures, and whether the result actually proves impairment.

The Traffic Stop Was Unlawful – An officer must generally have reasonable suspicion of a traffic violation or criminal activity before stopping a vehicle. A stop based only on an unsupported hunch may violate the Fourth Amendment. Body-camera footage, dash-camera video, dispatch records, witness statements, and roadway evidence may contradict the officer’s description. If the court suppresses evidence obtained from an unlawful stop, the blood-test result and other evidence may become unusable.

The Officer Lacked Probable Cause for the DUI Arrest – A lawful traffic stop does not automatically justify arresting the driver or requesting post-arrest chemical testing. The officer must have sufficient grounds to believe the person committed DUI, DWAI, or another qualifying offense. The defense may show that alleged signs of intoxication had innocent explanations. Red eyes may result from allergies, poor balance from an injury, unusual speech from a medical condition, and nervous behavior from the stress of the stop.

The Blood Draw Was Conducted Without Valid Consent or a Lawful Warrant – Because a blood draw is a search of the body, law enforcement must have a lawful basis for obtaining the sample. That basis may include valid consent, a properly issued warrant, or a narrowly applicable legal exception. The defense may challenge whether consent was voluntary, whether the warrant affidavit established probable cause, or whether officers exceeded the authority granted by the warrant. An unlawful blood draw may lead to suppression of the result.

The Express Consent Requirements Were Not Followed – Colorado’s Express Consent Law contains requirements governing when chemical testing may be requested and how a refusal is determined. An officer’s failure to comply may affect the blood evidence, the refusal allegation, or the related DMV revocation. Relevant questions include whether the officer had reasonable grounds, whether the driver was properly advised, whether the requested test was appropriate, and whether the officer accurately documented the driver’s response.

An Unauthorized or Unqualified Person Drew the Blood – Colorado law limits who may perform forensic blood draws. The defense may investigate the person’s qualifications, job role, training, supervision, and the location where the sample was collected. If the prosecution cannot establish that the draw was performed by an authorized person, the defense may seek to exclude the result or reduce the weight given to it.

The Blood Draw Was Not Performed Properly – Errors during collection can affect the reliability of the sample. Problems may include using an improper antiseptic, failing to follow collection instructions, underfilling the tubes, failing to mix the sample with preservatives, or failing to seal the kit correctly. Medical records, collection forms, testimony, body-camera footage, and photographs of the kit may reveal departures from proper procedure.

The Sample Was Mislabeled – The blood tubes and accompanying documents should identify the person, collection time, collector, and case information. Missing, inconsistent, or altered information may create doubt about whether the laboratory tested the correct sample. Even a small discrepancy can become significant when the state cannot provide a reliable explanation tying the sample to the defendant.

The Chain of Custody Is Incomplete – The prosecution should be able to account for the sample from collection through laboratory testing. The chain of custody may identify who handled the evidence, when it was transferred, how it was stored, and when it arrived at the laboratory. Unexplained gaps, broken seals, undocumented transfers, or conflicting records may support an argument that the sample was contaminated, altered, or confused with another specimen.

The Sample Was Stored or Transported Improperly – Excessive heat, prolonged delays, improper refrigeration, damaged packaging, or leaking tubes can affect sample integrity. The defense may request storage logs, shipping documents, courier records, and laboratory receiving information. A failure to preserve the sample properly may make the final result less reliable, particularly when there are indications of fermentation or decomposition.

The Laboratory Used an Unreliable Testing Procedure – The laboratory must use scientifically accepted methods and follow its validated procedures. The defense may examine whether the analyst prepared the sample correctly, selected the correct method, used appropriate controls, and accurately calculated the result. A deviation from written procedures does not always require exclusion, but it can undermine the prosecution’s claim that the result is dependable.

Quality Control Samples Failed – Laboratories run controls, calibrators, and blanks to verify that the testing process is functioning correctly. Failed or out-of-range controls may show that the batch was not valid. The final report may not disclose every quality-control issue. A defense attorney may need the complete batch packet and raw data to determine whether the laboratory should have rejected or repeated the analysis.

The Instrument Was Not Properly Calibrated or Maintained – Forensic instruments require maintenance and calibration. Records may reveal recurring errors, repairs, failed checks, or instrument performance problems near the date of testing. The defense can examine whether the laboratory resolved these issues and whether the instrument was operating within the laboratory’s acceptance criteria during the defendant’s test.

The Sample Fermented or Degraded – Improper preservation or storage may allow biological changes to occur inside the tube. In an alcohol case, fermentation can potentially create ethanol after the sample was collected. The condition of the sample, preservative concentration, storage history, glucose level, microbiological activity, and laboratory findings may all be relevant. An independent toxicologist can evaluate whether the reported alcohol could have been affected by post-collection changes.

The Reported Result Falls Within the Laboratory’s Measurement Uncertainty – A result close to a significant threshold should not necessarily be treated as exact. Every quantitative laboratory measurement includes some degree of uncertainty. For example, when a reported BAC is near 0.08, the uncertainty range may become important to whether the state can reliably establish a per se violation. The defense may ask a forensic toxicologist to explain the range and its significance.

The Driver’s BAC Was Rising – Alcohol can continue entering the bloodstream after drinking has stopped. A person’s BAC may therefore be lower while driving than it is when blood is drawn later. The defense may reconstruct the drinking timeline using receipts, witness statements, surveillance video, food consumption, and the time of the stop and draw. This evidence may support the argument that the driver was below 0.08 while operating the vehicle.

Retrograde Extrapolation Is Unreliable – Prosecutors sometimes use retrograde extrapolation to estimate a driver’s earlier BAC from a later blood result. This calculation requires assumptions about when drinking ended, whether alcohol absorption was complete, the person’s elimination rate, and other individual factors. When the underlying facts are unknown, the estimate may be speculative. Cross-examination can expose assumptions that make the calculation unreliable.

A Positive Drug Test Does Not Prove Impairment – Many drugs can remain in the blood after their most significant impairing effects have diminished. A prescription medication may also be present because the driver was taking it lawfully and as directed. The prosecution must connect the laboratory result to actual impairment. Normal driving, clear speech, steady movement, appropriate behavior, and strong performance on roadside exercises may conflict with the claim that the detected drug impaired the driver.

The THC Result Does Not Establish Guilt – A delta-9 THC result of five nanograms or more may permit an inference of impairment, but it does not create an automatic conviction. Tolerance, timing, the driver’s behavior, and the remaining evidence may rebut that inference. Frequent cannabis users may have measurable THC despite displaying few or no signs of impairment. The defense can challenge both the laboratory evidence and the prosecution’s interpretation of it.

The Blood Result Conflicts With the Other Evidence – A high alcohol or drug concentration may be questionable when video shows safe driving, coherent speech, good balance, appropriate responses, and no substantial signs of impairment. The defense may compare the laboratory report with the officer’s contemporaneous observations, body-camera footage, hospital records, witness testimony, and booking video. Significant inconsistencies can create reasonable doubt.

The Driver Did Not Actually Refuse the Blood Test – A refusal may be disputed when the driver asked questions, expressed fear of needles, requested a different valid test, had difficulty understanding the officer, or was physically unable to cooperate. Audio and video evidence may show that the person did not clearly refuse or that the officer did not adequately explain what was required. The precise conversation can be critical at the DMV hearing and in court.

A Medical Condition Prevented the Blood Draw – Some people have medical conditions that make a blood draw unusually difficult or dangerous. Others may be unable to cooperate because of injuries sustained in a crash, unconsciousness, confusion, or emergency medical treatment. The defense may argue that inability should not be treated as an intentional refusal. Medical records and testimony from healthcare providers can help establish why the test was not completed.

Independent Retesting Produces a Different Result – The defense may be able to request preservation of the remaining blood sample and arrange for independent testing. A second laboratory may identify a different concentration, contamination, insufficient sample volume, or another problem. Independent analysis can be especially important when the original result is close to a legal threshold or when the initial laboratory records reveal possible quality-control issues.

The Prosecution Cannot Prove the Charge Beyond a Reasonable Doubt – A blood-test report is only one part of the case. Prosecutors must still prove that the defendant drove or was in actual physical control of a vehicle and met the legal definition of DUI, DUI per se, or DWAI. Problems with the stop, arrest, blood draw, sample integrity, testing method, interpretation, or other evidence may combine to create reasonable doubt. Depending on the circumstances, the result may be suppression, dismissal, acquittal, or negotiation of a reduced charge.

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Frequently Asked Questions

Can I choose a blood test instead of a breath test?
In many alcohol-related DUI investigations, blood and evidential breath testing may both be available. The driver’s ability to choose can depend on the circumstances, availability of testing, and whether the officer suspects drugs in addition to alcohol.

Is a blood test required when police suspect drugs?
Blood testing is commonly requested in drug-DUI cases because evidential breath instruments do not detect marijuana, prescription medications, or most controlled substances. Refusing a lawfully requested drug test may create license consequences under Colorado’s Express Consent Law.

Does a positive blood test automatically mean I am guilty?
No. The state must establish that the sample was lawfully obtained, properly handled, accurately tested, and connected to the defendant. In most drug cases, prosecutors must also prove that the substance impaired the person’s ability to drive.

What BAC can result in a DUI charge?
For most drivers who are 21 or older, a BAC of 0.08 or higher may support DUI per se. A lower result may still be used in a DUI or DWAI prosecution when other evidence allegedly shows impairment.

Can I be charged if my BAC was below 0.08?
Yes. A driver may be charged with DWAI or DUI based on driving conduct, officer observations, field sobriety evidence, statements, drug results, or a combination of substances.

What does a BAC of 0.15 mean?
A chemical-test BAC of 0.15 or higher results in a Persistent Drunk Driver designation. This can create additional alcohol education, treatment, ignition-interlock, and license-reinstatement requirements.

How long after driving can police take a blood sample?
A sample should generally be obtained as soon as reasonably practicable. A delay does not necessarily make the test inadmissible, but it can affect how accurately the result reflects the alcohol or drug concentration while the person was driving.

Can the police take my blood without my consent?
Police may seek a warrant authorizing a nonconsensual blood draw. Limited statutory or constitutional exceptions may also be asserted in particular cases. The legality of any involuntary draw depends on the specific facts.

Who is allowed to draw blood for a Colorado DUI test?
Colorado law restricts forensic blood draws to authorized medical or qualified personnel. The collector’s identity and qualifications should be documented and may be reviewed by the defense.

Can hospital blood results be used in a DUI case?
Potentially. Medical blood testing performed for treatment purposes differs from a forensic blood draw, but prosecutors may seek medical records through lawful legal process. Questions can arise concerning privacy, collection methods, laboratory methods, and whether the hospital result is comparable to a forensic whole-blood result.

Why might a hospital result differ from a police blood test?
Hospitals may test serum or plasma, while forensic DUI testing commonly analyzes whole blood. These are not necessarily interchangeable, and the reported concentrations may differ. Collection timing and laboratory methods can also affect the results.

Can my attorney have the blood independently tested?
In many cases, the defense can seek access to the remaining sample for independent analysis. The ability to retest depends on whether enough blood remains and whether the sample has been properly preserved.

What drugs can a DUI blood test detect?
The substances tested depend on the laboratory panel and the officer’s request. Testing may include marijuana-related compounds, stimulants, opioids, sedatives, prescription medications, and other controlled substances.

Does prescribed medication provide a defense to DUI?
A valid prescription may explain why the drug was present, but it does not automatically prevent a DUI charge. Colorado law prohibits driving when medication impairs the person’s ability to operate safely, even if the drug was lawfully prescribed.

Is five nanograms of THC an automatic DUI in Colorado?

No. A result of at least five nanograms of active delta-9 THC per milliliter permits an inference that the person was under the influence, but it is not an automatic per se conviction. The inference may be challenged with evidence concerning tolerance, behavior, timing, and lack of impairment.

What happens if I refuse a blood test?
A first refusal generally results in a one-year license revocation, a second refusal in a two-year revocation, and a third or subsequent refusal in a three-year revocation. Refusal also creates Persistent Drunk Driver consequences and may be introduced in the criminal case.

How long do I have to request a DMV hearing?
A person accused of refusing a test generally must request a hearing within seven days of the arrest. When a blood result later shows an alcohol concentration that triggers a per se action, the hearing request generally must be made within seven days after receiving notice of the result.

Can I drive while waiting for the blood results?
The answer depends on whether another license restraint applies. In many blood-test cases, the person may retain driving privileges until the laboratory result is reported and the DMV issues notice, but the exact status should be confirmed from the temporary permit, notice, and DMV record.

Can a blood-test result be excluded from court?
Yes, in some cases. A court may suppress or exclude the result if the blood was obtained through an unconstitutional search, the prosecution cannot establish the necessary evidentiary foundation, or another serious legal defect occurred. Other problems may affect the weight of the result rather than its admissibility.

Do I need an attorney before the blood results come back?
Waiting can make it harder to preserve evidence and prepare for the DMV deadline. An attorney can begin obtaining video, identifying witnesses, reviewing the legality of the arrest, and preparing to evaluate the laboratory records before the final report is issued.

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Additional Resources

Colorado Division of Motor Vehicles – Alcohol DUI – The Colorado DMV explains the state’s Express Consent Law and the license consequences associated with chemical testing and refusal. It also identifies the officer-requested blood test and evidential breath test as the recognized methods of satisfying the alcohol chemical-testing requirement.

Colorado Division of Motor Vehicles – DUI Administrative Process – The DMV provides information about the separate administrative license proceeding, including when a hearing request must be filed after a refusal, breath test, or blood-test result.

Colorado Department of Public Health and Environment – Alcohol and Drug Testing Laboratories – CDPHE certifies forensic toxicology laboratories that analyze blood and other biological samples for alcohol and drugs. Certification depends on inspection or accreditation, proficiency testing, and compliance with Colorado’s testing rules.

Colorado General Assembly – Colorado Drunk Driving Laws – The Colorado General Assembly publishes a summary of DUI, DUI per se, DWAI, underage drinking and driving, license consequences, and criminal penalties. The summary also directs readers to the controlling provisions of Title 42 of the Colorado Revised Statutes.

Colorado Revised Statutes – Colorado’s DUI and chemical-testing laws are primarily located in Title 42, including the statutes governing DUI offenses, Express Consent testing, administrative revocations, and sentencing. The General Assembly provides access to the current Colorado Revised Statutes.

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Colorado DUI Blood Test Attorney | Denver, CO

A blood-test result may become one of the most important pieces of evidence in a Colorado DUI case, but it should not be accepted without a complete investigation. The legality of the draw, the qualifications of the collector, the condition of the collection kit, the chain of custody, the storage history, the laboratory’s procedures, and the interpretation of the result may all affect the strength of the prosecution’s case.

If you were arrested after submitting to or refusing a blood test, Colorado DUI defense attorney Matthew Martin can review the evidence and explain your legal options. Acting quickly is especially important because the DMV hearing deadline may begin only days after an arrest or receipt of the blood-test notice.

Call 303.725.0017 today to schedule a free consultation with The Law Office of Matthew Martin. Your case will be carefully reviewed, and the firm will work to protect your driving privileges, criminal record, reputation, and future.

The Law Office of Matthew A. Martin, P.C. represents clients throughout the greater Denver area, including Douglas County, Jefferson County, Adams County, Arapahoe County, Boulder County, Broomfield County, and Denver County.

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