When people think about impaired driving, they often focus on blood alcohol concentration levels and breathalyzer results. In reality, many serious Houston car crashes involve drivers who are impaired even though their BAC is below the legal limit or was never accurately measured. Alcohol, illicit drugs, prescription medications, or a combination of substances can significantly impair driving ability without producing a clear or timely BAC result.

At Hollingsworth Law Firm, our Harris County personal injury attorneys regularly handle cases where impairment is a central issue, even though traditional alcohol testing fails to capture the whole picture. Understanding how impairment is proven under Texas law is critical for injured victims seeking accountability after a serious crash.

Why BAC Results Are Often Incomplete or Misleading

BAC testing is not always a reliable snapshot of a driver’s condition at the time of a crash. In many Houston collisions, testing occurs well after the incident, sometimes hours later. During that time, alcohol levels may rise or fall, depending on when the driver last consumed alcohol.

Several factors can limit the usefulness of BAC results:

• Delayed testing due to medical treatment or transport.
• Incomplete testing when officers prioritize emergency response.
• Refusal to submit to testing.
• BAC levels that fall below the legal limit but still impair judgment and reaction time.

Texas law does not require a specific BAC level to prove impairment in a civil injury case. The question is whether the driver was impaired and whether that impairment contributed to the crash.

Alcohol Impairment Below the Legal Limit

Many drivers believe they are safe to drive as long as they remain under the legal BAC threshold. In practice, impairment often begins well before that point. Alcohol affects vision, coordination, decision-making, and reaction time even at low levels.

In Houston injury cases, impairment may be established through:

• Officer observations such as slurred speech, balance issues, or delayed responses.
• Field sobriety test performance.
• Witness accounts describing erratic driving behavior.
• Video footage from body cameras, dash cameras, or nearby businesses.
• Crash dynamics that suggest delayed braking or poor judgment.

A low BAC does not shield a driver from civil liability if evidence shows alcohol contributed to unsafe driving.

Drug Impairment Without Alcohol

Illicit drugs and controlled substances are increasingly involved in serious crashes across Texas. Unlike alcohol, many drugs do not have universally accepted impairment thresholds. This makes drug impairment cases more complex but no less provable.

Drugs commonly involved in Houston crashes include:

• Marijuana, which affects perception and reaction time.
• Cocaine and methamphetamine, which impair judgment and increase risk-taking.
• Opioids, which slow response and reduce alertness.
• Benzodiazepines, which cause drowsiness and confusion.

Toxicology reports may identify the presence of drugs without specifying the level of impairment. In these cases, courts rely on circumstantial evidence and expert testimony to establish how the substance affected the driver’s ability to operate a vehicle safely.

Prescription Medications and Legal Impairment

Many drivers are legally prescribed medications that still impair driving. Pain medications, muscle relaxers, sleep aids, and anti-anxiety drugs can all interfere with coordination and awareness.

Prescription drug impairment cases often involve:

• Warning labels advising against driving.
• Dosage changes or recent prescriptions.
• Combining medications with alcohol.
• Medical records showing known side effects.
• Expert analysis linking the medication to observed driving behavior.

Under Texas law, a driver can be impaired even if the medication was legally prescribed and taken as directed. The key issue is whether the driver knew or should have known that driving posed a danger.

Evidence Texas Courts Consider in Impairment Cases

Because impairment is not limited to BAC results, Texas courts evaluate a broad range of evidence in civil injury cases.

This evidence often includes:

• Police reports and officer testimony.
• Body camera and dash camera footage.
• Toxicology results and lab reports.
• Medical records from emergency treatment.
• Witness statements describing driving behavior.
• Cell phone data showing distraction or drug-related activity.
• Expert testimony from toxicologists or medical professionals.

When viewed together, this evidence can establish impairment even when chemical testing alone is inconclusive.

Why Impairment Cases Require Careful Investigation

Insurance companies frequently argue that without a high BAC, impairment cannot be proven. This is not accurate under Texas law, but it is a common defense strategy. These cases require careful investigation to ensure critical evidence is preserved and correctly interpreted.

Delays can be costly. Toxicology evidence may be incomplete. Video footage can be overwritten. Witness memories fade. Early legal involvement is often essential to building a complete picture of impairment.

How Hollingsworth Law Firm Builds Impairment Cases

At Hollingsworth Law Firm, we look beyond breathalyzer results. Our attorneys investigate all potential sources of impairment and how they contributed to a crash.

We work to:

• Analyze toxicology and medical records.
• Obtain and preserve video evidence.
• Interview witnesses and first responders.
• Consult with toxicology and medical experts.
• Demonstrate how impairment affected driving behavior and crash dynamics.

Our goal is to ensure that impaired drivers are held fully accountable, even when traditional alcohol testing fails to tell the whole story.

Contact Hollingsworth Law Firm Today

If you were injured in a Houston car crash involving a driver impaired by alcohol, drugs, or prescription medication, you deserve a thorough investigation and informed legal representation. Hollingsworth Law Firm is prepared to evaluate the evidence, explain your options, and pursue accountability under Texas law.

Contact our Houston office today at 713-637-4560 or online to schedule a free consultation.

About The Author

Steve Hollingsworth

Steve Hollingsworth is a seasoned trial attorney with extensive experience across Texas. After beginning his career as a felony prosecutor, Steve went on to represent major insurance companies before focusing on helping individuals injured in car, motorcycle, trucking accidents, and premises liability cases. Founder of his own firm, Steve is committed to providing personalized, client-focused legal representation to ensure justice for those he serves.