In a Texas DWI case, few pieces of evidence attract more attention than a breath-test number.
- 0.07
- 0.09
- 0.14
- 0.16
Once a number appears on a report, it can seem as though the entire case has been reduced to a decimal.
It has not.
A breath-test result is evidence produced by a particular instrument, operated under particular procedures, at a particular time after the alleged driving.
At Taylor Defense Firm, we examine the process that produced the number as well as the number itself.
- Why was the driver stopped?
- What evidence existed before the breath test?
- Was the testing procedure properly followed?
- Was the instrument functioning properly?
- What records exist for the instrument?
- How much time passed between driving and testing?
- And what does the reported result actually establish under Texas law?
What Is a DWI Breath Test?
A breath-alcohol test analyzes a breath specimen to estimate alcohol concentration for purposes of a DWI investigation.
It is different from a roadside field sobriety test.
Field sobriety tests generally evaluate observed physical or divided-attention performance.
Breath testing produces a chemical-test result.
Both may become evidence, but they answer different questions.
Texas Has Two Basic Intoxication Theories
Texas law generally permits intoxication to be established by:
- not having the normal use of mental or physical faculties because of alcohol, drugs, controlled substances, dangerous drugs, combinations of substances, or another substance introduced into the body;
- or
- having an alcohol concentration of 0.08 or more.
A breath result may therefore become particularly important under the alcohol-concentration theory.
But it should still be considered with the complete evidence.
A Breath Machine Does Not Test the Driver While Driving
This sounds obvious, but it matters.
The alleged offense occurs while the person is operating the motor vehicle.
Breath testing ordinarily occurs later.
The sequence may be:
driving → traffic stop → roadside investigation → field sobriety testing → arrest → transportation → breath-test procedure.
The result reflects the specimen obtained during testing.
The timeline between driving and testing should therefore be established rather than ignored.
What Happened Before the Breath Test Still Matters
A breath-test case does not begin at the police station.
Before the test, there may have been:
- a traffic stop;
- officer observations;
- statements;
- field sobriety testing;
- a search;
- arrest;
- transportation; and
- a request for a specimen.
Constitutional and evidentiary issues arising earlier in the investigation do not disappear merely because a later breath result exists.
The Testing Procedure Matters
Breath testing depends upon an established testing process.
Depending upon the particular evidence and program involved, records may concern:
- the instrument;
- test sequence;
- operator;
- observation period or procedural safeguards;
- reference or control checks;
- instrument records;
- maintenance;
- technical supervision;
- test documentation; and
- the reported result.
The defense should determine whether the procedures applicable to the particular test were followed.
Who Operated the Instrument?
Breath testing involves a human operator as well as an instrument.
Relevant questions can include:
- Who administered the test?
- What qualifications did that person possess?
- What procedure did the operator follow?
- What observations were made before testing?
- Were any problems noted?
- Were multiple specimens obtained?
- Was the test sequence completed normally?
The operator's testimony can be compared with test records and available video.
Instrument Records Can Matter
The result generated in one defendant's case is only part of the available information.
Depending upon the circumstances, relevant records may include information concerning:
- inspections;
- maintenance;
- repairs;
- reference checks;
- reported errors;
- service history;
- certification records;
- test logs; and
- other documentation associated with the instrument.
The existence of a maintenance entry does not automatically invalidate a test.
Likewise, a machine's general approval does not mean the records from the particular test should never be examined.
Observation Before Testing Can Matter
Breath testing procedures commonly include safeguards intended to reduce the possibility that events immediately before testing affect the specimen.
The defense may examine what happened during the relevant pre-test period.
Was the driver:
- observed;
- speaking;
- coughing;
- burping or belching;
- putting anything into the mouth;
- vomiting;
- receiving medical attention; or
- otherwise experiencing something documented by the officer?
The legal significance depends upon the actual procedure, evidence, and applicable scientific principles.
Mouth Alcohol Can Be an Issue
Breath-alcohol testing is intended to produce a reliable measurement associated with alcohol concentration, not merely detect alcohol remaining in the mouth.
Testing procedures and instrument safeguards are designed in part to address potential contamination concerns.
When the evidence raises a legitimate issue involving mouth alcohol, regurgitation, recent consumption, or another relevant circumstance, the underlying records and procedure should be examined.
The existence of such a possibility does not automatically invalidate a result.
It creates a question that should be evaluated scientifically rather than assumed.
Two Breath Samples Can Provide Useful Information
Breath-testing protocols may generate more than one specimen result.
Comparing those results can be important.
The defense may examine:
- How close were the results?
- Were both accepted?
- Did the instrument report an error?
- Was additional testing attempted?
- Did the procedure satisfy applicable requirements?
The complete test record is more informative than simply quoting the highest number.
Video Can Show the Breath-Test Procedure
If testing is recorded, video may preserve:
- the driver's condition;
- instructions;
- the specimen request;
- the driver's response;
- the pre-test period;
- the testing sequence;
- difficulties providing a specimen;
- officer comments; and
- events not obvious from the written paperwork.
Video can corroborate the records or reveal issues requiring further examination.
What If the Result Is .08 or Higher?
An alcohol concentration of 0.08 or more falls within Texas's statutory definition of intoxication.
That can be powerful evidence.
But a defense analysis still asks:
- Was the stop lawful?
- Was the test admissible?
- Was the procedure reliable?
- Was the instrument functioning properly?
- What time was the test performed?
- What does the result establish about the time of operation?
A result above .08 does not erase those questions.
What If the Result Is Below .08?
A breath result below .08 does not automatically require dismissal of a Texas DWI case.
The State may attempt to prove that the accused did not have the normal use of mental or physical faculties.
Prosecutors may rely upon:
- driving;
- field sobriety performance;
- speech;
- balance;
- admissions;
- officer observations;
- other substances; and
- video.
The defense may likewise use the breath result and other evidence to challenge the prosecution's theory.
The .15 Threshold Can Change the Offense Level
Texas Penal Code §49.04 contains a significant enhancement involving alcohol concentration.
If an analysis of the person's blood, breath, or urine shows an alcohol concentration of 0.15 or more at the time the analysis was performed, the DWI offense can be elevated from the ordinary Class B misdemeanor to a Class A misdemeanor.
That changes the ordinary maximum punishment from:
- 180 days in county jail and a $2,000 fine
to:
- one year in county jail and a $4,000 fine.
The exact reported concentration can therefore affect both the State's intoxication evidence and the classification of the offense.
A Result Near .15 Deserves Particular Attention
When the reported result is near a statutory threshold, the analytical process becomes especially important.
Questions concerning:
- accepted specimens;
- precision;
- instrument performance;
- applicable testing rules;
- records;
- timing; and
- the statutory language
may become significant.
A reported number should not be treated as more exact than the testing process supports.
Alcohol Concentration Changes Over Time
Alcohol is absorbed and later eliminated.
Depending upon when drinking occurred, a person's alcohol concentration can be rising or falling during the period between driving and testing.
That means a later breath result does not necessarily establish the precise alcohol concentration at every earlier moment.
The chronology matters.
Retrograde Extrapolation Is Not Just Subtraction
Estimating a person's earlier alcohol concentration from a later result may involve retrograde extrapolation.
A reliable analysis can depend upon information such as:
- time of last drink;
- amount consumed;
- drinking pattern;
- food;
- time of driving;
- time of testing;
- absorption status; and
- appropriate scientific assumptions.
Simply taking a later number and mechanically subtracting alcohol per hour can oversimplify the science.
Breath Testing Does Not Identify Every Intoxicating Substance
A conventional alcohol breath test concerns alcohol.
It does not establish the presence or concentration of every drug capable of producing intoxication.
A person suspected of drug-related intoxication may be investigated through other evidence, potentially including:
- blood toxicology;
- officer observations;
- field sobriety evidence;
- drug-recognition evidence;
- prescription information;
- statements; and
- video.
A low alcohol result therefore does not necessarily end an investigation when police claim another substance caused impairment.
What Happens If the Driver Refuses?
A driver may decline a requested breath specimen.
A refusal can create consequences separate from the ultimate question of guilt in the criminal DWI case.
Texas implied-consent law can create administrative driver's-license consequences associated with refusal.
Police may also seek other legally authorized evidence depending upon the circumstances.
The exact request, warnings, response, and subsequent police actions should be identified.
Refusal Is Not the Same as a Failed Breath Test
These terms should not be confused.
A person may expressly refuse.
Another person may attempt to provide a specimen but be unable to complete the testing procedure.
Another test may be interrupted by an instrument or procedural issue.
The records and video may show what actually happened.
The label placed on the event should match the evidence.
Breath and Blood Cases Are Different
Both can produce alcohol-concentration evidence.
But they reach the result differently.
Breath evidence involves a breath-testing instrument and its associated procedures.
Blood evidence involves a biological specimen, collection, chain of custody, laboratory analysis, and associated scientific data.
A defense strategy should address the evidence actually used rather than treating all BAC evidence as interchangeable.
What Punishment Can a Breath-Test DWI Carry?
The breath test itself does not determine the entire punishment range.
A basic first DWI is generally a Class B misdemeanor, carrying:
- 72 hours to 180 days in county jail; and
- a possible fine up to $2,000.
A qualifying alcohol concentration of 0.15 or greater at the time of analysis can elevate the DWI to a Class A misdemeanor, generally carrying:
- up to one year in county jail; and
- a possible fine up to $4,000.
Qualifying prior intoxication convictions can increase the offense level further, including felony punishment in appropriate cases.
Serious bodily injury or death can lead to separate felony intoxication offenses.
Build the Breath Case From Stop to Result
At Taylor Defense Firm, we may reconstruct breath-test evidence as:
driving → traffic stop → officer observations → field sobriety testing → arrest → specimen request → implied-consent warnings → transport/testing location → pre-test procedure → breath specimens → instrument records → reported result → timing → charging decision.
We then ask:
- Was the stop lawful?
- What evidence of intoxication existed before testing?
- What exactly was requested?
- Did the driver consent, refuse, or attempt the test?
- Was the operator qualified?
- Was the required testing procedure followed?
- What do the instrument records show?
- Were any errors or irregularities documented?
- What does video show?
- How much time passed after driving?
- Is the reported result above a statutory threshold?
- And what does the complete evidence actually prove about intoxication while operating?
A breath-test number can be some of the State's strongest evidence.
But the number was produced by a process. A meaningful DWI defense examines both.