When a DWI case can be dismissed
A DWI case gets dismissed when a judge finds that the prosecution lacks enough evidence to prove guilt beyond a reasonable doubt, or when police violated your constitutional rights during the stop, arrest, or testing. This is different from winning at trial — a dismissal ends the case before it reaches a verdict. The most common reasons are problems with how the traffic stop happened, errors in breath or blood testing, or violations of your right to counsel or to remain silent.
Dismissals are not automatic. A DWI lawyer files motions asking the judge to throw out evidence or the entire case, and the judge decides whether the law was followed. The outcome depends entirely on what actually happened during your arrest and what records exist to prove it.
Key Takeaways
- A DWI case can be dismissed if police lacked reasonable suspicion to stop your vehicle, or if the stop itself violated traffic laws or your rights.
- Breath and blood tests can be excluded from evidence if the equipment was not properly maintained, the officer was not certified, or the test procedure did not follow state rules.
- You have a right to refuse a breath test at the roadside (the portable device), though refusing a blood test at the station carries separate penalties.
- A lawyer reviews police reports, dashcam and bodycam footage, and maintenance records for testing equipment to find grounds for dismissal motions.
- Dismissal motions must be filed before trial, usually within weeks of your arrest, so timing matters.
Problems with the traffic stop itself
Police need reasonable suspicion — a specific, articulable reason — to stop your vehicle. Weaving between lanes, speeding, a broken taillight, or running a red light all count. A hunch or a profile does not. If the officer's report says they stopped you but does not describe what you actually did wrong, or if dashcam footage shows you were driving normally, a judge may find the stop was unlawful.
Once the stop is unlawful, everything that follows — the field sobriety tests, the breath test, statements you made — can be excluded as "fruit of the poisonous tree." The case often collapses without that evidence. A lawyer obtains the dashcam footage from the police department and compares it to the officer's written report. If they do not match, that is grounds for a dismissal motion.
The officer also must follow traffic laws during the stop. If they pulled you over in an unsafe location, did not use proper lighting, or detained you longer than necessary to issue a citation, those violations can also lead to dismissal.
Breath test errors and equipment problems
Breath testing machines are calibrated devices that require regular maintenance and operator training. If the machine was not calibrated within the required timeframe — usually every six months, but this varies by state — the results are unreliable. If the officer administering the test was not certified, or if the test procedure did not follow your state's rules (such as a required waiting period before testing), the results can be excluded.
A lawyer requests maintenance and calibration records from the police department or the testing facility. These records are public and must be provided. If records are missing, incomplete, or show the machine was out of calibration on the date of your test, the judge will likely exclude the breath result.
You also have a right to observe the test and to request an independent test at your own expense. If police refused either of these, that is another ground for exclusion. Some states also require an officer to watch you for a set period before the test to make sure you did not eat, drink, or vomit — if that did not happen, the result is questionable.
Blood test collection and handling
Blood tests are more complex than breath tests because the sample must be collected, stored, and transported correctly. The person drawing blood must be trained and licensed. The sample must be preserved with the right chemical additive and kept at the right temperature. The chain of custody — the documented record of who handled the sample and when — must be unbroken.
A lawyer requests the blood draw kit documentation, storage records, and chain of custody paperwork. If the kit was expired, if the sample sat at room temperature for hours, or if the chain of custody has gaps, the results can be challenged. Some states also allow you to have the sample retested at an independent lab, and if that test shows a different result, it raises questions about the original test's reliability.
Blood tests also require a warrant in most states unless you consented in writing. If police drew blood without a warrant and without your written consent, the entire test result is excluded, even if the test itself was done correctly.
Field sobriety tests and observation
Field sobriety tests — the walk-and-turn, one-leg stand, and horizontal gaze nystagmus (eye movement) test — are subjective. An officer's interpretation of whether you passed or failed is not objective fact. Poor lighting, uneven pavement, medical conditions, age, and fatigue all affect performance, but the officer's report may not mention these factors.
A lawyer reviews the dashcam or bodycam footage to see how the tests were actually performed and scored. If the video shows you performed better than the officer's report claims, or if the officer did not follow the standardized procedure, that undermines the prosecution's case. Some states also require specific training for administering these tests, and if the officer was not trained, the results are inadmissible.
The officer's observations of impairment — slurred speech, bloodshot eyes, the smell of alcohol — are also subjective. A lawyer can challenge whether these observations were actually present or whether they were assumptions based on the stop itself.
Your right to counsel and to remain silent
If police questioned you after arrest without reading you your Miranda rights, or if you asked for a lawyer and they continued questioning you, statements you made are excluded from evidence. This does not mean the case is dismissed, but it removes a key piece of prosecution evidence.
You also have the right to refuse a breath test at the roadside (the portable device used during the stop). Refusing that test cannot be used against you in court, though it may trigger an automatic license suspension under your state's implied consent law. At the police station, you can refuse a blood or breath test, but the consequences are different — refusal itself can be used as evidence, and your license suspension is usually longer.
A lawyer reviews the police report and any recordings to see whether your rights were honored. If they were not, motions to suppress statements or test results follow.
How a lawyer files for dismissal
A DWI lawyer files a motion to suppress evidence or a motion to dismiss the case. These are written requests to the judge, supported by facts from police reports, recordings, maintenance records, and informed analysis. The lawyer argues that evidence was obtained illegally or is unreliable, or that the prosecution cannot prove guilt beyond a reasonable doubt.
The prosecution then files a response, and the judge holds a hearing where both sides present arguments. The judge decides whether to grant or deny the motion. If granted, the evidence is excluded or the case is dismissed. If denied, the case proceeds to trial.
These motions must be filed before trial, usually within 30 to 60 days of your first court appearance, depending on your state. Missing the important date can mean you lose the right to challenge the evidence. This is why timing and early legal review matter.
What happens after a dismissal
If a case is dismissed, the charges are dropped and you are not convicted. However, the arrest record may still exist. Some states allow you to petition to have the arrest record sealed or expunged after a dismissal, which means it does not show up on background checks. The rules for this vary by state and by the reason for dismissal.
If your license was suspended under implied consent law (for refusing a test or failing a test), a dismissal does not automatically restore it. You may need to file a separate petition with the Department of Motor Vehicles or the court to get your license back.
Frequently Asked Questions
Can a case be dismissed if I failed the breath test?
Yes, if the breath test result is excluded from evidence due to equipment problems, procedural errors, or an unlawful stop. Without that test, the prosecution may not have enough evidence to prove impairment. A lawyer reviews the test records and the circumstances of the stop to find grounds for exclusion.
What if I refused the breath test — does that help my case?
Refusing the roadside breath test (the portable device) cannot be used against you in court. However, refusing a blood or breath test at the police station can be used as evidence, and your license suspension is usually longer. A lawyer can still challenge whether police had legal grounds to request the test in the first place.
How long does it take to get a case dismissed?
Dismissal motions are typically filed within 30 to 60 days of your first court appearance. A judge may rule on the motion within weeks, or it may take several months depending on the court's schedule. If the motion is denied, the case proceeds to trial.
Do I need a lawyer to file for dismissal?
You can file motions yourself, but DWI cases involve technical rules about evidence, testing procedures, and constitutional rights. A lawyer knows which records to request, how to interpret them, and which arguments work in your state's courts. Most people who represent themselves do not succeed in getting cases dismissed.
If my case is dismissed, does the arrest disappear from my record?
A dismissal means you are not convicted, but the arrest record usually remains. Many states allow you to petition to seal or expunge the record after a dismissal, which removes it from public view. The rules vary by state, so ask your lawyer about the process in your jurisdiction.