Colorado DUI Defenses

Illegal Traffic Stop Defense

Police officers must have reasonable suspicion to stop a vehicle. If the initial stop was unlawful, evidence gathered afterward may potentially be suppressed.

Common issues include:

• Minor driving behavior that does not justify a stop
• Anonymous tips lacking corroboration
• Improper checkpoint procedures
• Stops based on hunches rather than objective facts

In some cases, suppression of evidence can substantially weaken the prosecution’s case.

Learn more about challenging unlawful stops on our Illegal Traffic Stop DUI Defense page.

Challenging Breath Test Results

Breath test results are not automatically accurate. Multiple factors can affect the reliability of breath testing devices.

Potential defenses may involve:

• Improper calibration or maintenance
• Failure to follow observation procedures
• Mouth alcohol contamination
• Medical conditions such as GERD
• Radio frequency interference
• Operator error

Even where a breath result appears high, the surrounding circumstances and reliability of the testing process still matter.

Read more on our Challenging Breath Test Results page.

Challenging Blood Test Results

Blood testing is often viewed as stronger evidence than breath testing, but blood results can still be challenged.

Potential issues include:

• Improper storage or handling
• Contamination
• Fermentation
• Chain of custody problems
• Laboratory error
• Delays in testing

Blood testing cases often involve technical and scientific issues that require careful review of records and procedures.

Additional information is available on our Challenging Blood Test Results page.

Rising Blood Alcohol Defense

Alcohol absorption takes time. A person’s blood alcohol concentration may continue rising after driving has already occurred.

This defense commonly arises when:

• A driver consumed alcohol shortly before driving
• Testing occurred significantly later
• The prosecution attempts retrograde extrapolation
• The driver appeared less impaired than the chemical result suggests

The key issue in many DUI per se cases is the BAC at the time of driving—not simply the BAC at the time of testing.

Visit our Rising Blood Alcohol Defense page to learn more.

DUI Refusal Defense

Colorado’s express consent law allows the DMV to revoke a driver’s license following a refusal to submit to chemical testing. However, refusal cases can still be defended.

Potential issues may include:

• Improper advisement by law enforcement
• Confusion regarding testing requests
• Medical inability to complete testing
• Ambiguous or unclear refusals
• Violations during the investigation

Refusal allegations can affect both the criminal case and DMV proceedings.

For additional information, review our DUI Refusal Defense and Express Consent resources.

Field Sobriety Test Defenses

Field sobriety tests are subjective and often affected by factors unrelated to alcohol impairment.

Potential issues may include:

• Uneven surfaces
• Weather conditions
• Injuries or medical limitations
• Anxiety or nervousness
• Fatigue
• Improper instructions from officers
• Non-standardized testing methods

Many people who are completely sober may still struggle with divided-attention exercises.

Read more on our Field Sobriety Test Defense page.

Lack of Actual Physical Control

A person may face DUI charges even if the vehicle was not actively moving. Colorado law permits prosecution where someone allegedly exercised “actual physical control” over a vehicle while impaired.

These cases often involve:

• Sleeping in parked vehicles
• Vehicles parked on the roadside
• Questions regarding intent to drive
• Keys located inside the vehicle
• Inoperable vehicles

Actual physical control cases are highly fact-specific.

Learn more on our Actual Physical Control DUI Defense page.

Medical Conditions Mistaken for Intoxication

Some medical conditions can resemble signs of alcohol or drug impairment.

Examples may include:

• Diabetes
• Neurological disorders
• Fatigue
• Anxiety
• Balance disorders
• Speech impairments
• Injuries
• Prescription medication side effects

Police officers are not medical professionals, and symptoms may sometimes be misinterpreted during roadside investigations.

Learn more on our Medical Conditions Mistaken for Intoxication page.

Defending Marijuana and Prescription Drug DUI Charges

Colorado DUI law also applies to drugs, including marijuana and legally prescribed medications.

Unlike alcohol cases, DUID allegations often focus heavily on officer observations and subjective evidence.

Defenses may involve:

• Lack of actual impairment
• Tolerance issues
• Problems with toxicology interpretation
• Timing of ingestion
• Medical prescription use
• Weak observational evidence

These cases frequently require detailed review of toxicology evidence and the surrounding circumstances.

See our Marijuana DUI Defense and Prescription Drug DUI Defense pages for additional information.

DUI Accident Defense

An accident alone does not prove intoxication or impairment.

In DUI accident cases, important issues may include:

• Whether impairment actually caused the collision
• Road or weather conditions
• Independent negligence by another driver
• Accident reconstruction evidence
• Injuries affecting behavior or appearance
• Reliability of witness statements

These cases often involve both criminal allegations and potential civil consequences.

Learn more on our DUI accident defense page.