Unlawful Stop or Arrest
Lack of Reasonable Suspicion for Traffic Stop
Police must have specific, articulable facts that a crime is occurring or has occurred before initiating a traffic stop. Stops based solely on a hunch or vague claims like “driving late at night” are not legally sufficient. A defense lawyer will closely examine dashcam footage and police reports to uncover unlawful stops and seek to have evidence suppressed.
Lack of Probable Cause for Arrest
Even after a stop, officers must establish probable cause before making an arrest. Probable cause requires objective facts supporting a DWI charge, not mere suspicion. An attorney will often argue that the officer’s observations were exaggerated or misinterpreted.
Unlawful or Prolonged Detention
Detaining a driver beyond the time necessary to complete the purpose of the stop without additional reasonable suspicion violates Fourth Amendment rights. Prolonged detentions can occur when police delay while awaiting a DWI unit or unnecessarily prolong questioning. Challenging detention timelines can be a powerful defense strategy.
No Actual Physical Control of the Vehicle
In Texas, “operating” a motor vehicle is required for a DWI conviction. If a person is merely sitting in a parked car without intent to drive, and no evidence shows recent operation, an attorney can argue that the operation element is missing and seek dismissal.
Procedural & Constitutional Violations
Failure to Read Miranda Rights / Custodial Interrogation Violations
If police question a suspect in custody without first providing Miranda warnings, any resulting statements may be suppressed. Defense attorneys regularly challenge statements obtained without proper Miranda warnings, which can significantly weaken the State’s case, depending on the particular facts of an arrest.
Illegal Search or Seizure
DWI cases often involve searches for blood evidence. Blood draws require a valid warrant or proper consent. Common problems with blood warrants include:
- Lack of probable cause in the affidavit
- Defective warrants lacking magistrate signatures
- Stale information supporting the warrant If a warrant is defective, a DWI lawyer can file a motion to suppress the blood evidence, often leading to a favorable resolution.
Police Misconduct or Coercion
Improper pressure on a suspect can invalidate evidence. For example, if officers misinform a driver about legal consequences of refusing a breath test (such as threatening longer license suspensions than actually exist or the possibility of being charged for not cooperating with the police), any consent given may not be considered valid. Misleading conduct by police can be a significant basis for suppression motions and keeping a breath or blood result out of court.
Field Sobriety Test Defenses
Improperly Administered SFSTs
Standardized Field Sobriety Tests (SFSTs) like the Walk and Turn or Horizontal Gaze Nystagmus must be administered strictly according to NHTSA guidelines. Deviation from the protocol undermines their reliability and can render them inadmissible. A DWI defense attorney will often cross-examine the arresting officer to expose improper administration.
Subjective Interpretation or Environmental Factors
Field tests are highly subjective. Poor lighting, uneven ground, high winds, and nervousness can affect performance. Challenging the environmental conditions at the time of the test can create reasonable doubt about the reliability of the officer’s conclusions.
Physical or Medical Conditions Affecting Performance
Medical issues such as back injuries, neurological disorders, balance problems, or age-related conditions can mimic intoxication clues. A lawyer can present expert testimony or medical records to explain how medical issues may have led to a wrongful DWI arrest.
Chemical Test Defenses
Improper Breath or Blood Test Procedures
Breath and blood tests must adhere to strict procedures. Breath tests require a 15-minute observation period to prevent contamination, and blood tests must use properly maintained equipment and trained personnel. Failure to comply with required procedures can result in suppressed or discredited results.
Unreliable Breathalyzer or Equipment Malfunction
Breath machines must be properly calibrated and maintained. Maintenance logs and calibration records are crucial. Malfunctions, skipped maintenance, or improper operation can be powerful areas to attack in a DWI defense.
Contaminants or External Factors (Mouth Alcohol)
Mouth alcohol contamination from substances like mouthwash, belching, dental appliances, or acid reflux can cause falsely high readings. An experienced DWI defense lawyer knows how to investigate and expose these factors to undermine breath test results.
Rising Blood Alcohol Content (BAC)
A person’s BAC can continue to rise after they stop drinking but before chemical testing occurs. Retrograde extrapolation evidence can sometimes demonstrate that the defendant was below the legal limit while driving. This defense can be especially effective when there is a long delay before testing.
Medical Conditions Affecting BAC Accuracy
Conditions such as GERD, diabetes, and hypoglycemia can interfere with breath or blood tests. An experienced Houston DWI attorney will work with medical experts to explain these factors to the jury.
Gender or Physiological Variability
Breath tests assume a “one size fits all” partition ratio (blood-to-breath alcohol concentration) that does not account for gender, body temperature, or lung capacity differences. Challenging these assumptions can weaken the reliability of the State’s chemical evidence.
Lab & Scientific Challenges
Improper Chain of Custody or Sample Handling
The prosecution must prove an unbroken chain of custody for blood samples. Any gaps, delays, or mislabeling can create doubt about the reliability of the evidence. Houston DWI defense attorneys carefully scrutinize every step in the evidence handling process.
Flawed Forensic Lab Procedures or Analyst Errors
Forensic labs are not infallible. Cross-contamination, clerical errors, and unqualified or careless analysts can all undermine test results. A defense lawyer will review lab records and may consult independent experts to challenge the State’s evidence.
Lack of Time-of-Driving BAC Data
The prosecution must prove intoxication at the time of driving, not at the time of testing. If there is a significant delay, retrograde extrapolation becomes speculative. Raising doubts about the timing of BAC measurements can lead to acquittals.
Evidentiary & Strategic Defenses
Insufficient Evidence to Prove Intoxication Beyond a Reasonable Doubt
The State must meet a high burden. If the evidence is circumstantial, conflicting, or lacking credibility, the defense can argue that the State failed to prove intoxication beyond a reasonable doubt. Houston defense attorneys are skilled at highlighting gaps and inconsistencies.
Eyewitness Testimony Supporting Sobriety
Testimony from friends, passengers, or bartenders who observed the defendant shortly before the arrest and saw no signs of intoxication can significantly bolster a defense. DWI attorneys use such testimony to challenge the credibility of police observations.
Successful Motion to Suppress Evidence
If key evidence (such as a blood test, confession, or SFST results) is excluded due to procedural or constitutional violations, the State’s case may collapse. Winning a suppression motion can often lead to reduced charges or outright dismissals.
Conclusion
DWI defense in Texas demands a thorough analysis of every stage of the investigation and arrest. At Ceja Law Firm, Board-Certified Criminal Defense Attorney Jose Ceja utilizes extensive experience and proven strategies to identify weaknesses in the prosecution’s case and fight aggressively for the best possible outcome.
If you are facing a DWI charge, contact a trusted DWI attorney at Ceja Law Firm today for a free consultation.
