Colorado DWAI vs. ‘Per Se’ DUI: How Impairment Is Proven Without 0.08% BAC

Colorado has two different drunk driving charges that work in separate ways. The standard In Colorado, you don’t need a 0.08% BAC to face drunk driving charges. The state recognizes two separate offenses: DUI (Driving Under the Influence) and DWAI (Driving While Ability Impaired), and the difference between them can mean serious consequences. A DWAI doesn’t rely on hitting that 0.08% threshold; prosecutors can convict you with a BAC as low as 0.05% if your ability to drive was affected “to the slightest degree.” Even minor signs like slurred speech, red eyes, or unsteady movements during a traffic stop can be used as evidence of impairment. That means your behavior on the roadside and how an officer interprets it can weigh just as heavily as your breath or blood test results. Understanding how Colorado law defines and proves impairment is essential to protecting your rights and your driving record.

Understanding Colorado’s Three-Tiered Impaired Driving Framework

Most states use two categories for drunk driving charges. Colorado law creates three separate drunk driving offenses based on blood alcohol concentration (BAC) measurements and how much the driver’s abilities have declined.

Driving While Ability Impaired (DWAI) occurs when a driver’s BAC measures between 0.05% and 0.079%. Law enforcement can also charge DWAI when alcohol, marijuana, or other drugs reduce driving skills even slightly. A motorist showing minor coordination problems or small judgment errors may face DWAI charges.

Driving Under the Influence (DUI) requires prosecutors to prove that alcohol or drugs substantially reduced the driver’s ability to operate a vehicle safely. Officers document substantial impairment through field sobriety tests, driving patterns, and physical symptoms. DUI charges typically accompany BAC readings of 0.08% or higher, but the prosecution must demonstrate actual driving impairment beyond the chemical test results.

Per Se DUI creates an automatic violation when breath tests, blood tests, or urine tests show BAC at or above 0.08%. Colorado law treats this threshold as proof of intoxication without requiring additional evidence of impaired driving behavior. The chemical test result itself establishes the offense.

This graduated structure gives district attorneys flexibility to match criminal charges with the defendant’s level of intoxication and observed impairment.

Traffic safety officers can pursue appropriate penalties whether a driver shows minimal impairment (DWAI), clear functional decline (DUI), or meets the legal intoxication threshold (Per Se DUI).

Defense attorneys must understand each offense’s distinct elements when representing clients facing impaired driving accusations in Colorado courts.

How DWAI Differs from DUI

DWAI works differently from DUI per se charges. With DUI per se, the law automatically assumes you are impaired at 0.08% BAC or higher. With DWAI, prosecutors must prove that your driving ability decreased by any measurable amount. The law’s “slightest degree” phrase creates Colorado’s lowest level for impaired driving charges. This means police can arrest you and prosecutors can charge you with DWAI even when your BAC stays below the standard 0.08% limit.

How Colorado’s “Per Se” DUI Law Works at 0.08% and Above

Per se DUI laws remove the prosecutor’s need to prove a driver was actually impaired once blood alcohol content (BAC) reaches 0.08% or higher. Colorado Revised Statutes § 42-4-1301(1)(a) states that driving a motor vehicle with a BAC at or above 0.08% counts as DUI automatically. How the person drove or whether they showed signs of intoxication does not matter. The breathalyzer or blood test result by itself proves guilt.

This legal standard works differently from DWAI (Driving While Ability Impaired) charges. DWAI cases require prosecutors to show evidence that alcohol affected the driver’s ability to operate the vehicle safely, even slightly. Per se DUI violations function as strict liability offenses for the BAC measurement element.

Defense attorneys in per se DUI cases focus on challenging the testing process itself. Common defense approaches include questioning whether law enforcement properly calibrated the breath testing device, whether officers followed correct procedures during the traffic stop and testing, and whether the sample collection and storage met legal requirements. Arguments about safe driving performance rarely succeed in per se cases.

Reaching the 0.08% BAC threshold activates mandatory legal consequences. The Colorado Department of Revenue automatically suspends the driver’s license. Courts may impose jail sentences ranging from five days to one year, depending on prior DUI convictions.

Convicted drivers must complete alcohol education programs and may face ignition interlock device requirements. Fines, community service, and probation commonly accompany these penalties.

The per se standard applies to all drivers age 21 and older operating vehicles on Colorado roads and highways. Commercial drivers face a lower 0.04% BAC threshold, and drivers under 21 face stricter penalties under zero tolerance laws at 0.02% BAC or higher.

Impairment-Based DUI: When BAC Numbers Don’t Tell the Whole Story

In Colorado, a BAC of 0.08% automatically qualifies as a “per se” DUI, but lower numbers don’t guarantee safety from charges. Prosecutors can still pursue a DUI if they prove a driver was impaired, even with a BAC below 0.08%.

During a stop, officers look for physical and behavioral clues: slurred speech, red or watery eyes, the smell of alcohol, and poor coordination on field sobriety tests. Dashcam footage, witness statements, and erratic driving patterns all help build an impairment-based case.

Because alcohol affects everyone differently, factors like body weight, tolerance, medication use, or fatigue can heighten impairment at lower BAC levels. In Colorado, drivers testing between 0.05% and 0.079% can still face conviction if prosecutors show their ability to drive was reduced “to the slightest degree.”

Even when the numbers seem low, the evidence of impairment can still tell a powerful story in court.

Observable Signs of Impairment That Officers Document

When police officers stop drivers, they write detailed reports about what they see and hear. These written observations become evidence that courts use to decide impairment cases. Officers record these signs to support charges for driving while ability impaired (DWAI) and driving under the influence (DUI), even when breath or blood tests show alcohol levels below the legal limit.

Police documentation covers several types of impairment signs that district attorneys present during criminal trials.

Law enforcement officers record these observable signs:

• Physical appearance signs: red or watery eyes, red facial skin, unclear speech patterns, smell of alcoholic beverages from the person or vehicle

• Movement problems: dropping driver’s license or insurance cards, trouble getting out of the car, unable to stand without swaying

• Roadside sobriety test results: unable to complete the walk-and-turn test, cannot balance on one leg, horizontal gaze nystagmus (involuntary eye movement)

• Driving behavior problems: crossing lane markers, changing speeds without reason, slow response to traffic signals, breaking traffic laws

Police officers add dashboard camera video and body-worn camera recordings to their written reports.

This video evidence shows what the officer saw during the traffic stop. Courts use these recordings to verify the officer’s written statements about driver behavior and physical condition.

Field Sobriety Tests and Their Role in Proving Impairment

Colorado police rely on standardized field sobriety tests (SFSTs) to determine if a driver is impaired enough for a DWAI or DUI arrest. The National Highway Traffic Safety Administration (NHTSA) approves three key tests that are scientifically validated and widely accepted in court.

• Horizontal Gaze Nystagmus (HGN): Officers move a pen or finger side to side while watching for involuntary eye jerking that increases with alcohol consumption. The angle which the jerking begins helps estimate BAC levels.

• Walk-and-Turn: Drivers walk heel-to-toe in a straight line, turn, and walk back. Officers note eight possible clues of impairment, including balance loss, stepping off the line, or not following directions.

• One-Leg Stand: Drivers must balance on one foot while counting aloud for 30 seconds. Swaying, hopping, or using arms for balance indicates divided attention problems linked to intoxication.

More clues across multiple tests strengthen probable cause for arrest. Courts carefully review whether officers followed NHTSA procedures, since improper administration can make the results unreliable. Bodycam and dashcam footage often confirm how tests were conducted, helping determine if the evidence is admissible.

Physical Indicators: Bloodshot Eyes, Slurred Speech, and Other Evidence

Beyond sobriety tests, officers rely on visible physical symptoms to prove impairment, especially in DWAI cases where BAC levels fall between 0.05% and 0.079%.

Common signs include:

• Red or watery eyes from dilated blood vessels

• Slurred speech or difficulty forming words

• Alcohol odor from breath, clothes, or the vehicle

• Poor coordination when exiting the car or walking

These indicators are captured in bodycam footage, dashcam video, and written reports. When combined, they form a strong narrative of impairment even without high BAC readings.

Medical research supports that alcohol disrupts coordination, speech, and balance—all governed by the central nervous system. While defense lawyers often question each observation, multiple consistent symptoms give prosecutors compelling evidence in court.

Driving Behavior as Probable Cause for Impaired Driving Charges

Before making a DUI stop, Colorado officers must have reasonable suspicion—a legal standard based on specific driving behavior suggesting impairment.

Typical signs include:

• Weaving within or across lanes

• Fluctuating speeds without reason

• Drifting over road lines

• Failing to move at green lights or stop signs

• Driving unusually slow, creating a hazard

Even one minor infraction, combined with erratic movement, can justify a stop under the Colorado DUI law. Dashcam footage and officer notes serve as key evidence showing the stop was lawful.

To secure a conviction, prosecutors must link this observed driving behavior with additional proof, such as physical signs of intoxication, failed field sobriety tests, or chemical test results.

Ultimately, the state must prove that a driver’s ability to operate a vehicle safely was compromised, even if their BAC wasn’t above the per se limit.

Officer Testimony and Training in Detecting Impairment

Police officers act as the main witnesses in Colorado DWAI and DUI cases. They tell the court what they saw and explain how they tested drivers for impairment.

Officers learn special skills to spot and record signs that someone is impaired. Their training matters because judges look at whether officers know what they’re doing and follow the correct procedures. An officer’s background and methods can determine whether someone is convicted or found not guilty.

What Officers Learn and Do

NHTSA Field Sobriety Test Training – Officers take approved courses from the National Highway Traffic Safety Administration. These courses teach them the right way to give three standard roadside tests: the horizontal gaze nystagmus test (checking eye movement), the walk-and-turn test, and the one-leg stand test. Each test has specific steps and scoring rules.

Drug Recognition Expert Programs – Some officers receive advanced training to identify impairment from marijuana, prescription medications, methamphetamine, cocaine, and other drugs. The DRE protocol includes a 12-step evaluation process that examines blood pressure, muscle tone, pupil size, and other physical signs.

Recording What They See – Officers write down specific details about a driver’s condition: slurred words, bloodshot eyes, dilated or constricted pupils, inability to follow simple instructions, lack of balance, and fumbling movements. These observations become evidence in court.

Testifying in Court – Officers must explain their technical training and findings using clear language. Criminal defense attorneys will question their methods, their memory of events, whether they followed proper procedures, and any mistakes they made. Officers prepare to answer these challenges while maintaining the accuracy of their reports.

Colorado courts rely on officer credibility when determining guilt in impaired driving cases. The quality of police training and documentation directly affects trial outcomes and plea bargaining decisions.

Chemical Testing Refusals and Their Impact on Impairment Cases

When drivers refuse breath tests or blood tests in Colorado, they face automatic administrative penalties that exist apart from criminal charges. Colorado’s Express Consent Law creates a one-year license revocation for first-time offenders who refuse chemical testing.

Prosecutors can present evidence of refusal during criminal trials. They argue the refusal shows the defendant knew they were guilty. The refusal removes the most measurable proof of intoxication: blood alcohol concentration (BAC) test results. This elimination can help the defense in DWAI cases (Driving While Ability Impaired), where specific BAC levels make significant differences in charges and penalties.

Without chemical test data, prosecutors must build their case using only officer observations, field sobriety test performance, and circumstantial evidence like driving patterns or the smell of alcohol. Defense attorneys challenge these subjective assessments because they depend on individual officer judgment rather than scientific measurement.

The decision to refuse testing involves weighing two competing factors. On one side stands immediate administrative consequences: the guaranteed one-year license loss under the Express Consent Law. On the other side sit potential trial advantages, especially in borderline impairment cases.

In these borderline situations, BAC evidence might have shown levels above the 0.05% DWAI threshold but below the 0.08% DUI threshold. The absence of this numerical evidence forces the state to prove impairment through less reliable methods.

Field sobriety tests like the horizontal gaze nystagmus, walk-and-turn, and one-leg stand rely on officer interpretation. Medical conditions, physical disabilities, nervousness, and environmental factors affect performance on these tests.

Without BAC numbers to support officer conclusions, defense attorneys can create reasonable doubt about the actual level of impairment at the time of driving.

Penalties for DWAI Versus DUI Convictions in Colorado

Both DWAI and DUI convictions in Colorado lead to actions against your driving privileges. The punishment depends on how serious the offense is and whether you have prior convictions.

The Department of Motor Vehicles handles license suspensions or revocations separately from what happens in criminal court. This means you face two different sets of consequences at the same time.

The administrative penalties affect your driving record in several ways. The DMV adds points to your driver’s license. You must meet specific requirements before getting your license back. You may need to install an ignition interlock device in your vehicle.

DUI convictions cause longer suspension periods than DWAI offenses. Getting your license back after a DUI also requires meeting stricter conditions.

The state maintains detailed records of these violations in the Colorado Division of Motor Vehicles database. Each conviction type triggers different mandatory assessment periods and restoration procedures under Colorado Revised Statutes Title 42.

License Suspension and Administrative Consequences for Both Offenses

When a court finds a driver guilty, the Department of Motor Vehicles enforces different penalties for DWAI and DUI charges. DUI charges lead to stricter punishments that limit a person’s ability to drive legally.

Administrative penalties include:

• First DWAI offense adds eight points to a driver’s record. The DMV does not automatically suspend the driver’s license, but may add restrictions when too many points build up on the driving record.

• First DUI conviction requires the state to revoke the driver’s license for nine months. The driver can apply to get the license back after one month if they agree to install an ignition interlock device in their vehicle.

• Express Consent revocations happen outside of criminal court. When drivers refuse to take a breath, blood, or urine test, or when test results show blood alcohol concentration above 0.08%, the DMV automatically suspends driving privileges. This administrative action occurs whether or not criminal charges result in a conviction.

• Point assessment differences affect car insurance costs and create more serious outcomes for future violations. A DUI conviction places twelve points on the driving record, while a DWAI conviction places eight points.

Insurance companies use these point totals to calculate premium rates, and accumulated points can trigger additional license suspensions.

How Drug Impairment Cases Differ From Alcohol-Related Charges

Drug impairment cases in Colorado work differently from alcohol DUI cases. The main difference is the lack of a clear legal limit for drugs like marijuana, similar to how alcohol has the 0.08% blood alcohol content standard.

Colorado law sets 5 nanograms of THC per milliliter of blood as a marker for marijuana impairment. A court can consider this level as evidence of impairment. The driver can challenge this assumption because scientists disagree about whether this number proves impairment.

Prosecutors build drug impairment cases using multiple types of evidence:

• Drug Recognition Expert officers who receive special training to identify drug impairment

• Police observations of the driver’s behavior and physical condition

• Performance on roadside sobriety tests

• Blood test results showing drug presence

The body processes alcohol and marijuana in different ways. Alcohol leaves the body at a steady, predictable rate. THC (the active chemical in marijuana) stays in the bloodstream much longer than its effects last. A person can test positive for THC days or weeks after use, even when no longer impaired.

This scientific problem creates challenges for both sides. Defense attorneys can question whether a positive drug test proves current impairment. Prosecutors must show the driver was actually impaired at the time of driving.

Chemical test results alone do not prove the case. The prosecution needs witness testimony, officer observations, dashcam footage, and expert analysis to demonstrate impairment beyond a reasonable doubt.

Building a Defense Against Impairment-Based Charges

Fighting drunk driving charges means finding problems with the state’s case. Defense lawyers look at three main areas: why the police stopped the driver, what the officer saw, and how the field sobriety tests were done. A DUI attorney checks if police violated constitutional rights like Fourth Amendment protections against illegal searches and if officers followed proper legal procedures.

Main defense methods include:

• Questioning the officer’s credibility by showing conflicts in what the officer said, a lack of National Highway Traffic Safety Administration (NHTSA) training, or mistakes in following standardized field sobriety test protocols.

• Challenging field sobriety test validity by proving medical conditions like vertigo or inner ear problems, physical limitations such as knee injuries or back pain, or environmental factors like uneven pavement or poor lighting that affected test performance.

• Attacking subjective observations by showing other reasons for signs police claim show impairment, like fatigue from working long shifts, nervousness from being pulled over, or allergies causing red eyes.

• Examining dash cam and body camera footage to find differences between what the videos show and what officers claim happened during the traffic stop.

Expert witnesses like toxicologists, medical doctors, and retired police officers give important testimony about test accuracy, health conditions that mimic intoxication symptoms, and correct DUI assessment procedures.

These experts help challenge the prosecutor’s version of events by providing scientific evidence and professional opinions that support the defense theory of the case.