Can Breathalyzer Machine Errors Be Used to Defend a Texas DWI Case?

Many people assume that once a Breathalyzer machine reports a blood alcohol concentration over the legal limit, a DWI conviction is inevitable. In reality, breath testing equipment is not infallible. Like any scientific instrument, Breathalyzer devices require proper maintenance, calibration, operation, and recordkeeping to produce reliable results. When mistakes occur, the accuracy of the test may be questioned.

If you were arrested for DWI in Longview or elsewhere in East Texas, your breath test result is only one piece of evidence. An experienced DWI defense attorney may investigate whether problems with the testing equipment or procedures affected the reliability of the prosecution’s case.

How Breath Testing Works

Breath testing devices do not directly measure the amount of alcohol in your bloodstream. Instead, they estimate blood alcohol concentration by analyzing alcohol present in a person’s breath and applying a mathematical conversion ratio.

This process relies on several assumptions, including that the testing equipment is functioning correctly and that the person being tested fits the average physiological model used by the machine.

Because these assumptions are not always accurate, breath test results can sometimes be challenged.

Breathalyzer Machines Require Regular Maintenance

Breath testing instruments must be routinely inspected and maintained to ensure they continue operating properly.

Maintenance typically includes:

• Calibration checks
• Performance testing
• Software verification
• Replacement of worn components
• Accuracy testing
• Documentation of repairs

If maintenance records reveal missed inspections, overdue servicing, or repeated malfunctions, those issues may affect confidence in the reported results.

An experienced DWI defense attorney may obtain maintenance and calibration records to determine whether the machine was operating properly on the date of the arrest.

Calibration Errors Can Affect Accuracy

Calibration ensures that a Breathalyzer machine reports accurate readings.

Over time, even properly functioning instruments may drift outside acceptable accuracy ranges if they are not recalibrated.

Calibration problems may cause a machine to:

• Overestimate alcohol concentration
• Produce inconsistent readings
• Report inaccurate results
• Generate false positives

Even a relatively small measurement error may become important when a reported result is close to the legal limit.

Operator Error Can Influence the Test

Even if the machine itself functions properly, the person administering the test must follow established procedures.

Errors may occur if an officer:

• Fails to observe the required waiting period
• Improperly operates the instrument
• Conducts the test too soon after the driver consumed alcohol
• Uses the wrong testing procedure
• Fails to document required information

Testing procedures exist for a reason. When officers fail to follow them, the reliability of the results may become questionable.

Certain Medical Conditions May Affect Breath Test Results

Not every elevated breath reading is caused solely by alcohol impairment.

Several medical conditions may influence breath testing, including:

• Acid reflux
• Gastroesophageal reflux disease (GERD)
• Diabetes
• Hiatal hernias
• Certain respiratory conditions

For example, acid reflux may cause alcohol from the stomach to enter the mouth, potentially affecting the breath sample analyzed by the testing instrument.

Certain medical issues may also produce chemical compounds that interfere with some testing technologies.

Residual Mouth Alcohol Can Produce Higher Readings

Breath testing is intended to measure deep lung air, not alcohol remaining inside the mouth.

Residual mouth alcohol may result from:

• Recent alcohol consumption
• Mouthwash
• Dental products
• Burping
• Vomiting
• Acid reflux episodes

To reduce this risk, officers generally must observe the individual for a designated period before administering the breath test.

If proper observation procedures were not followed, the validity of the test may be challenged.

Environmental Factors May Affect Testing

Although Breathalyzer instruments are designed for law enforcement use, outside conditions can sometimes influence performance.

Potential issues include:

• Radio frequency interference
• Electrical problems
• Improper storage
• Temperature extremes
• Moisture exposure
• Mechanical malfunctions

Maintenance records and service history may reveal recurring problems with a particular instrument.

Breath Test Results Are Not the Entire Case

Prosecutors typically present breath test evidence together with:

• Officer observations
• Driving behavior
• Field sobriety testing
• Body camera footage
• Dash camera recordings
• Statements made by the driver

Weaknesses in the breath testing evidence may affect how the remaining evidence is viewed by prosecutors, judges, or juries.

A reported number above 0.08% does not automatically eliminate the possibility of a successful defense.

Reviewing the Records May Reveal Valuable Evidence

An experienced Texas DWI defense attorney may request and review documentation involving:

• Calibration records
• Maintenance logs
• Repair history
• Quality assurance reports
• Operator certifications
• Testing procedures

These records sometimes reveal deficiencies that are not apparent from the police report alone.

In some cases, repeated equipment issues or procedural errors may cast doubt on the reliability of the reported breath alcohol concentration.

Every Piece of Scientific Evidence Should Be Carefully Examined

Breath test evidence often appears convincing at first glance, but scientific evidence should never be accepted without careful review.

DWI prosecutions rely heavily on the assumption that testing equipment functioned correctly and that officers followed every required procedure. When those assumptions prove incorrect, important defense opportunities may exist.

Every Texas DWI case deserves a thorough investigation. Carefully examining the breath testing process, maintenance history, officer conduct, and scientific evidence may uncover weaknesses that significantly improve your defense.

Call The Law Office of Alex Tyra, P.C. For Your Free Consultation

If you’ve been charged with DWI in Longview or anywhere in East Texas, don’t wait. The clock starts ticking the moment you’re arrested, and every decision you make from here on out matters. The Law Office of Alex Tyra, P.C. is ready to help you protect your future, your license, and your wallet.

Call us today at (903) 753-7499 to schedule your free consultation and take the first step toward fighting your DWI charges.