When Can Evidence Be Suppressed in a DWI Case?
If you have been charged with the offense of driving while intoxicated (DWI), you might worry that the case against you is already decided. However, the important thing to keep in mind is that the prosecution must prove your guilt beyond a reasonable doubt. Without hard evidence, the state’s case can fall apart. Sometimes, evidence in a DWI case can be challenged or rendered inadmissible due to how it was obtained. A McKinney, Texas DWI defense attorney can review your case and file a motion to suppress any unlawfully obtained evidence.
At Texas Defense Firm, we have built a reputation for aggressive, strategic, and authoritative defense. In one notable case, Attorney Kyle Therrian challenged the admissibility of a client’s blood test results before trial for a second DWI charge. This had a significant impact on how the case was prosecuted, as it directly affected what evidence the state could bring forward.
Why Does Reasonable Suspicion Matter in DWI Cases?
Reasonable suspicion is the legal reason a police officer needs before pulling over a driver in Texas. An officer cannot stop you just because of a hunch or the time of night. The officer must point to specific facts that suggest criminal activity, such as weaving across lanes, speeding, or running a stop sign. Without those facts, the traffic stop may not be legal.
The traffic stop is often the first place a DWI defense lawyer looks for problems. If the officer lacked a valid reason to pull you over, everything found after the stop may be at risk. That can include the officer’s notes about your behavior, field sobriety test results, and breath or blood test results. Texas law bars the use of evidence that police obtain by breaking the law or violating the Constitution (Texas Code of Criminal Procedure Article 38.23).
Officers also need probable cause, which is a higher standard, before making an arrest. Probable cause means there are enough facts to make a reasonable person believe a crime happened. Dash camera and body camera videos sometimes tell a different story than the police report. A small drift inside a lane, for example, may not be enough to justify a stop on its own. A judge decides these questions at a hearing on a motion to suppress.
How Do Miranda Rights Work After a DWI Arrest in 2026?
Miranda rights are warnings police must give before questioning someone who is in custody. In 2026, these warnings still include the right to stay silent and the right to have a lawyer present. Once you are under arrest, police must give these warnings before asking questions that could be used against you.
Miranda warnings are not required at every point of a drunk driving stop. Questions on the side of the road, such as "Have you been drinking tonight?" usually come before an arrest. Courts often allow those answers as evidence. Miranda rules also do not apply to requests for a breath or blood sample. Those requests fall under the Texas implied consent law instead.
Miranda problems usually come up after the handcuffs go on. If an officer arrests a driver, places him or her in the patrol car, and then asks how many drinks the driver had without giving warnings, the answer may be kept out of court. Keep in mind that suppressing a statement does not always end the case, since the state may still rely on other evidence.
What Is Chain of Custody, and How Does It Affect DWI Evidence?
Chain of custody is the written record that tracks a piece of evidence from the moment police collect it until it reaches the courtroom. In a DWI case, the most common example is a blood sample. The record should show who drew the blood, who handled the vial, where it was stored, and when it went to the lab.
Each person who handles the sample is a link in the chain. A gap in that record raises real questions. Was the sample stored at the right temperature? Could it have been mixed up with another person’s vial? Was the kit sealed and labeled correctly? A defense lawyer can request lab files, storage logs, and testing records to look for these problems.
Breath tests come with their own records. Texas breath testing machines must be checked and kept in working order, and the officers who run them must be certified. Missing maintenance logs or an uncertified operator can weaken a breath test result.
Contact Our Dallas, TX DWI Defense Lawyers
A DWI arrest in Texas does not mean the evidence against you is ironclad. At Texas Defense Firm, we review each stage of your case, from the reason for the traffic stop to the handling of your blood or breath sample. We look for errors that may give you grounds to challenge the evidence in court. Contact our McKinney, Texas criminal defense attorneys or call 972-369-0577 to schedule a free consultation.