Intoxication manslaughter cases in Texas are some of the most challenging criminal cases to defend. The overwhelming majority of even the most experienced and talented criminal defense attorneys have never beaten intoxication manslaughter charges at trial, but Mark Thiessen has.
Mark is one of the few attorneys in Texas who has gotten a Not Guilty verdict from a jury for intoxication manslaughter (and he’s done it more than once). He’s the intoxication manslaughter lawyer in Texas, and if you or someone you love are facing intoxication manslaughter charges you need to give him a call.
Here’s what you’re up against: Those accused of intoxication manslaughter in Texas face serious penalties if convicted, including anywhere from 2–20 years in prison in addition to fines up to $10,000.
While beating these charges is tough, it is entirely possible — and we should know. Here are the five most effective defenses we use to fight these charges:
- Disproving intoxication
- Challenging causation
- Exposing constitutional violations
- Dismantling field sobriety tests
- Redefining “normal use”
Defending yourself starts with getting in touch with a Houston intoxication manslaughter attorney who has both tried and beaten intoxication manslaughter charges in court. Call Thiessen Law Firm today at (713) 864-9000 or contact us online for a free consultation with our team.
What is intoxication manslaughter?
What many people don’t realize is that intoxication manslaughter charges can apply even if you weren’t driving recklessly. You could be driving perfectly normally, get into an accident that wasn’t your fault, and still face these charges if you have alcohol in your system. That’s because under Texas Penal Code § 49.08, intoxication manslaughter occurs when:
- You operate a motor vehicle in a public place
- While legally intoxicated (BAC of 0.08% or higher, or loss of normal mental or physical faculties)
- And cause the death of another person by accident or mistake
Here’s what makes these cases particularly dangerous: the presence of alcohol in your system creates an automatic presumption of guilt in the minds of jurors, prosecutors, and even some judges. The moment alcohol becomes part of the narrative, many people stop looking for other explanations for what happened.
Despite how the prosecution may make it seem, an intoxication manslaughter charge is NOT a guaranteed conviction. The truth is, these cases hinge on scientific evidence that is far from perfect and legal presumptions that can be challenged by the right DWI attorney in Houston.
What is the sentence for intoxicated manslaughter in Texas?
In Texas, intoxication manslaughter is classified as a second-degree felony (yes, even if it’s a first time intoxication manslaughter conviction), carrying these potential consequences:
- Prison time: 2-20 years in the Texas Department of Criminal Justice
- Fines: Up to $10,000
- Driver’s license suspension: Up to 2 years
- Ignition interlock device: Required upon license reinstatement
- Felony record: Permanent impact on employment, housing, and voting rights
- Probation: Will include a minimum of 120 days in jail (day for day, no good time credit) up to 180 days, and will typically include strict conditions like regular drug testing, counseling, and community service.
The table below breaks down the penalties for various alcohol-related driving offenses in Texas, from standard DWI to the most serious charges like intoxication manslaughter in Houston.
| Offense | Charge | Jail time | License suspension | Fines |
| DWI first offense | Class B misdemeanor | 3 days – 180 days | 90 days – 1 year | Up to $2,000 |
| DWI first offense with a BAC greater than .15 | Class A misdemeanor | 30 days – 1 year | 180 days – 2 years | Up to $4,000 |
| DWI second offense | Class A misdemeanor | 30 days – 1 year | 180 days – 2 years | Up to $4,000 |
| DWI third offense | Third-degree felony | 2 – 10 years | 180 days – 2 years | Up to $10,000 |
| DWI w/ a child passenger | State jail felony | 180 days – 2 years | Up to 180 days | Up to $10,000 |
| Intoxication assault | Third-degree felony | 2 – 10 years | 180 days – 2 years | Up to $10,000 |
| Intoxication manslaughter | Second-degree felony | 2 – 20 years | 180 days – 2 years | Up to $10,000 |
Beyond the courtroom penalties for intoxication manslaughter, a conviction can carry devastating long-term consequences, including:
- Financial ruin: Civil lawsuits potentially in the millions, skyrocketing insurance rates, lost income during and after incarceration, ongoing monitoring costs
- Career destruction: Barred from numerous professions, permanent damage on background checks, termination of professional licenses, unexplainable employment gaps
- Devastation of your personal life: Relationship strain leading to divorce, negative child custody implications, social ostracism, housing difficulties
- Permanent legal limitations: Loss of gun rights, voting restrictions, enhanced penalties for future offenses, immigration issues, including possible deportation, limited access to education, and student loans
This is why Thiessen Law Firm approaches intoxication manslaughter cases with such intensity. We understand that what’s at stake isn’t just your freedom for a few years — it’s your entire future. By fighting aggressively at every stage, we’ve helped clients avoid these life-altering consequences entirely.
How we win intoxication manslaughter cases in Texas
1. Disproving intoxication
Prosecutors build their intoxication manslaughter cases on scientific evidence that isn’t nearly as reliable as they want jurors to believe. In intoxication manslaughter with a vehicle in Texas cases, the chemical testing methods used to measure blood alcohol concentration are fundamentally flawed.
- Breath tests can be compromised by everything from radio frequency interference to residual mouth alcohol to improper calibration.
- Blood tests, while generally more accurate, are vulnerable to improper storage, fermentation of the sample, and testing equipment errors.
Effective defense strategies thoroughly investigate the testing process, including equipment maintenance records, analyst qualifications, and lab quality control data. These discoveries can lead to evidence being thrown out entirely, dramatically weakening the prosecution’s case and often leading to reduced charges or outright dismissals.
2. Challenging causation
The link between alleged intoxication and the fatal accident is often the most attackable aspect of the prosecution’s case. Texas law requires prosecutors to prove beyond a reasonable doubt that intoxication directly caused the death — not just that the defendant had alcohol in their system when a tragedy occurred.
This causation element provides powerful ground for defense, especially when specialized accident reconstruction expertise is brought into the case, uncovering critical factors missed by initial investigations, such as faulty signals, road hazards, or mechanical failures. By demonstrating that these factors, not intoxication, were the true cause of the accident, defendants can successfully challenge the core elements of intoxication manslaughter charges.
3. Exposing constitutional violations
Fatal accident scenes create emotional pressure for law enforcement to quickly find someone to blame, often leading officers to overlook or deliberately bypass constitutional protections. Any skilled Houston intoxication manslaughter attorney should immediately investigate whether Fourth Amendment rights against unreasonable search and seizure or Fifth Amendment rights against self-incrimination were violated during the investigation.
Identifying these violations requires reviewing all available evidence:
- Body camera footage and dash camera recordings
- Dispatch communications and written reports
- Warrants and consent forms for blood draws
- Documentation of Miranda warnings
When constitutional violations are successfully exposed, evidence gets suppressed — often leaving prosecutors with insufficient proof to continue pursuing charges.
4. Dismantling field sobriety tests
Field sobriety tests create the illusion of scientific validity while actually relying on the subjective judgment of officers who already suspect intoxication. These flawed roadside exercises — the Horizontal Gaze Nystagmus (HGN), Walk-and-Turn, and One-Leg Stand tests — fail to account for countless variables that can affect performance regardless of sobriety.
The National Highway Traffic Safety Administration’s own research acknowledges significant error rates in these tests — as high as 35% even under ideal conditions. When these tests are conducted at accident scenes, with traumatized drivers, on uneven ground, or in poor lighting, their reliability drops even further. This creates an opportunity to challenge the severe sentence for intoxication manslaughter in Texas that would otherwise be imposed based on this questionable evidence.
5. Redefining “normal use”
The legal definition of intoxication in Texas includes the ambiguous standard of not having “normal use” of mental or physical faculties — a subjective determination that provides powerful grounds to challenge the prosecution’s case. This standard creates a weakness for prosecutors, as they must define what constitutes “normal” for a specific individual they likely just met.
Nobody knows your “normal” better than you and the people closest to you. Your unique physical characteristics, speech patterns, coordination, and mannerisms form your personal baseline that police officers have no familiarity with. Medical conditions like inner ear disorders, diabetes, neurological issues, anxiety, or even physical injuries can create symptoms that mimic intoxication but are actually just your normal state of being. Establishing this baseline through witness testimony, medical documentation, and potentially even video evidence of your typical behavior can directly contradict an officer’s subjective assessment.
The burden is on the prosecution to prove beyond a reasonable doubt that you were not normal at the time of the accident. When your defense team properly establishes what your actual baseline is, this burden becomes extraordinarily difficult for prosecutors to meet.
Real results: winning “Not Guilty” verdicts in intoxication manslaughter cases
While other Houston law firms talk about fighting for you, Thiessen Law Firm delivers actual results when it matters most. Mark Thiessen has secured Not Guilty verdicts in intoxication manslaughter cases that most attorneys would have plea-bargained away. We don’t just hope for reduced charges — we build winning strategies designed to exonerate our clients completely.
We have helped several people beat unfair intoxication manslaughter charges in court, and we’re always prepared to do it again for deserving clients who need our help. Here are just a few examples of how our scientific knowledge, aggressive trial tactics, and relentless preparation have saved clients from facing decades behind bars for intoxication manslaughter charges:
The “time of driving” defense
Here’s how we put this principle, also known in Texas as the “Time of Driving” rule, into focus in one of Mark Thiessen’s biggest cases ever, Texas vs. ZM:
- The client was driving home at 10 p.m. when he got into a horrible accident with another vehicle that left four passengers dead.
- To make tragic matters even worse, police responders neglected several key points in their investigation, including possible traffic light defects and a massive delay in issuing any sobriety analysis — the client wasn’t even asked to take a Breathalyzer until an hour and 45 minutes after the accident.
- While they eventually found the client’s BAC to be .14 blood and .10 breath, the results were collected too long after the fact to paint a compelling picture, but the numbers didn’t add up.
- Complicating matters, the client acted normally after the accident and was fully cooperative, even offering to take sobriety tests right there on the spot.
Outcome: The defense team fought hard and earned a Not Guilty verdict. This case demonstrates how even the most serious charges with multiple fatalities can be successfully defended when the right strategies are employed.
The “accident reconstruction” defense
In one remarkable case, Texas vs. TE, Mark Thiessen established that the accident wasn’t the driver’s fault, despite his intoxication. Here are the details:
- The defendant was facing 5–99 years for intoxication manslaughter due to a prior felony conviction.
- Despite a blood alcohol concentration (BAC) of .19 four hours after the accident, expert accident reconstruction demonstrated that the collision was beyond the defendant’s control.
- The reconstruction showed the victim pulled out in front of the defendant less than a second before impact, failing to yield right of way.
- Additionally, forensic toxicology revealed undeniable evidence of tampering with the defendant’s blood work, making the state’s evidence unreliable.
Outcome: The jury found the defendant guilty of the lesser included DWI, but Not Guilty of intoxication manslaughter. Instead of facing life imprisonment, the defendant walked away with time served — a dramatic difference.
The “exposing constitutional violations” defense
In cases where other defenses may not be viable, constitutional rights violations can still provide a path to a better outcome. Here’s how this strategy worked in Texas v. TP:
- The client had just been released from jail on a prior intoxication manslaughter conviction when his car slid off the freeway at a curve, crossed a grass median, and struck an oncoming vehicle, killing his passenger.
- After being airlifted to the hospital, the client’s blood was drawn without a warrant — revealing Xanax in his system but no alcohol.
- While the circumstances matched the legal standards for intoxication manslaughter, law enforcement failed to follow proper procedures for evidence collection.
- The warrantless blood draw violated the client’s Fourth Amendment rights, making the evidence potentially inadmissible in court.
Outcome: When confronted with this constitutional violation, prosecutors dismissed the intoxication manslaughter charges in favor of intoxication assault charges, reducing the potential sentence from 15 years in prison to just 2 years. This case underscores a vital principle: constitutional rights matter in every criminal case, regardless of the accusations.
Have more FAQs about DWI and intoxication manslaughter in Texas? Head to our blog!
Accused of intoxication manslaughter? Work with experienced defense from Thiessen Law Firm
Fighting intoxication manslaughter in Texas is one of the hardest tasks a lawyer can face. These cases require specialized knowledge of both criminal law and scientific evidence to challenge an intoxication manslaughter sentence that could forever change your life. But as our record shows, Mark Thiessen and his team at the Thiessen Law Firm are up to that task.
Mark Thiessen is a Triple Board Certified SuperLawyer, an ACS-CHAL Lawyer-Scientist, and he wins intoxication manslaughter cases. He has more than 125 Not Guilty verdicts and thousands of dismissals. Don’t risk betting the fight of your life on anything but the best. Contact us today to discuss your options and get your case off to the right start with a free consultation.
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