Can You Get a DUI With a 0.00 Breath Test?
A 0.00 breath result can rule out an important alcohol theory, but an alcohol breath tester does not test for most drugs. That can cause a DUI investigation to shift in a different direction.
Imagine being investigated for DUI, providing a breath sample, and seeing: 0.000.
The natural reaction is: "Then the DUI investigation is over, right?"
Not necessarily.
A zero breath alcohol result is highly relevant.
But an alcohol breath-testing instrument is designed to detect alcohol.
It does not ordinarily test for cannabis, prescription medications, stimulants, benzodiazepines, opioids, or most other drugs.
So a 0.00 breath result can significantly weaken or eliminate an alcohol-based explanation while leaving a different question open: Was the driver impaired by a drug?
A Breath Test Is Not a Universal Impairment Test
This distinction is fundamental.
An alcohol breath test answers a specific analytical question.
It does not directly determine whether someone is:
- Tired
- Ill
- Experiencing a medical issue
- Under the influence of cannabis
- Under the influence of a prescription medication
- Under the influence of a stimulant
- Under the influence of an opioid
- Affected by another substance
If the person's observed behavior appears inconsistent with the breath result, officers may investigate other potential causes.
What Happens After a 0.00 Breath Result?
The next step depends on the circumstances and jurisdiction.
An officer may:
- Reevaluate the initial observations
- Ask additional questions
- Request a Drug Recognition Expert
- Conduct additional impairment testing
- Seek a blood sample
- Investigate medications or drug use
- Consider a medical explanation
A zero result should cause the evidence to be reconsidered.
It should not simply be ignored because an arrest has already occurred.
This Is Where a DRE May Enter the Investigation
A certified Drug Recognition Expert (DRE) has specialized training in evaluating suspected drug impairment.
A DRE evaluation is broader than ordinary roadside field sobriety testing.
It can include:
- Interviews
- Preliminary examination
- Eye examinations
- Divided-attention testing
- Vital signs
- Pupil measurements under varying lighting conditions
- Muscle tone
- Examination for possible signs of drug administration
- Statements
- A drug-category opinion
- Toxicological testing
The DRE attempts to determine whether the observed impairment is consistent with one or more drug categories.
A DRE Opinion Still Requires Evidence
The fact that a DRE was called does not establish drug impairment.
The evaluation should make sense.
A review may ask:
- What signs of impairment were actually present?
- Did the person's behavior on video match the written description?
- Were the DRE procedures properly performed?
- Were expected signs for the suspected drug category present?
- Were signs expected for that category absent?
- Were medical explanations considered?
- Did toxicology support the opinion?
- How long after driving was the evaluation completed?
- How long after driving was blood collected?
The conclusion should follow from the observations.
What If the Blood Test Is Positive?
A positive blood toxicology result is important evidence.
But once again: presence is not automatically impairment.
The meaning of a positive result depends on the substance.
A positive THC result raises different interpretive issues than a stimulant.
A sedating prescription medication raises different issues than an inactive metabolite.
The concentration, timing, expected pharmacological effects, person's behavior, and DRE findings all matter.
What If the Blood Test Is Negative?
A negative toxicology result can raise significant questions, particularly when the investigation was based on suspected drug impairment.
But "negative" can also require context.
Laboratories have defined testing panels and analytical limits.
Not every possible substance is necessarily included in every screening or confirmation process.
The toxicology report should be reviewed to understand what was actually tested.
Could the Driver Simply Have a Medical Issue?
Potentially.
Behavior that appears abnormal is not automatically drug impairment.
Medical conditions, injuries, neurological issues, fatigue, anxiety, blood-sugar abnormalities, and other circumstances can sometimes resemble signs an officer associates with impairment.
One purpose of a careful evaluation is to consider whether the evidence supports a drug explanation or whether alternative explanations remain plausible.
That does not mean every unusual behavior has a medical explanation.
It means the possibility should not be dismissed without analysis.
What About SFSTs?
A drug DUI investigation may include Standardized Field Sobriety Tests:
- Horizontal Gaze Nystagmus
- Walk-and-Turn
- One-Leg Stand
But not every drug category produces the same expected findings.
This is particularly important with HGN.
A person should not be considered impaired by a particular drug simply because an officer wrote "HGN present" without considering whether HGN is expected for that drug category or whether the examination was properly performed.
The 0.00 Result Still Matters
It would be equally wrong to say:
"The breath test was zero, therefore nothing matters," and
"The breath test was zero, but we thought the person was impaired, so the result doesn't matter."
It matters.
It is objective evidence that should influence the investigation.
If the original theory was alcohol impairment, a 0.00 result requires that theory to be reconsidered.
Any new drug-impairment theory should then be supported by its own evidence.
What Objective Evidence Supports What Came Next?
Yes, a person may face a drug DUI investigation even after providing a 0.00 alcohol breath test.
But a zero breath result changes the case.
It means the evidence must support a theory other than alcohol.
That may involve:
- DRE evidence
- Blood toxicology
- Driving behavior
- Physical signs
- Statements
- SFST performance
- Video
- Medical considerations
- The complete timeline
At Legal Limit Consulting, drug DUI cases are evaluated by comparing each stage of the investigation with the evidence that follows.
Because when the breath test says 0.00, the correct question is not simply whether the officer still believed the driver was impaired.
It is: What objective evidence supports the explanation that came next?
Related reading: Prescription Medication DUI and THC Blood Tests.
This article provides general educational information, not legal advice or an opinion about any specific case. Standards, procedures, and evidentiary rules vary by jurisdiction.
If you are an attorney or individual seeking DUI case review, contact Legal Limit Consulting to discuss the case.