How DUI Lawyers Challenge Breathalyzer And Field Sobriety Test Results
by Arnab Dey Legal 31 May 2025
Breathalyzer and field sobriety tests are usually at the core of the prosecution in case you are arrested for DUI (driving under the influence). These tests are not fail-proof, though.
So, you can fight against the charges with the help of a DUI lawyer. An experienced DUI lawyer guides you through sobriety tests.
Moreover, they know how to attack the validity and dependability of this evidence may leave your case in pieces or have it dropped altogether.
In this article, we shall unpack the way DUI lawyers contest the results of the breathalyzer and the field sobriety tests in courts.
What Are The Limitations Of Sobriety Tests?
Even though sobriety tests are considered reliable indicators in DUI cases, they have numerous limitations.
And, because of these limitations, the results can be inaccurate and end up affecting you in the most unfair way possible. So, you can challenge the results of these tests in court.
Some of these limitations include:
Environmental Conditions:
Most sobriety tests are conducted on the roads, which are predominantly in bad environmental conditions. So, these external factors can affect the results of the sobriety tests.
Moreover, you need to understand that these field tests do not directly measure the intoxication percentage of the person. It just assumes intoxication based on circumstantial indicators.
Physical And Medical Conditions:
Due to certain medical and physical conditions, you might not be able to perform the sobriety tests properly.
And, if your officer overlooks this and puts you in a DUI case, then you have the right to challenge it in court. Moreover, you can question their judgment based on the sole result of the field tests.
Officer’s Subjective Judgement:
Given that sobriety tests are completely based on what the officer comes up with in their judgment, it can be subjective and inaccurate.
Moreover, a slight change in your attitude or your behavior can impact their subjective decisions. So, it is not a reliable test to determine whether you were driving under the influence of any substances.
How Can Sobriety Tests And DUI Cases Affect Your Business Reputation?
If you are a businessman or woman, you should know better than anyone that you are the face of your brand. So, any damage to your reputation can indirectly affect the reputation of your brand or business.
For instance, if you get involved in a DUI case because you failed the sobriety tests, your brand will face the consequences immensely.
Your consumers will stop their interactions with your brand and avoid you because of your DUI case. Moreover, you might stop getting potential clients to expand your business due to the reputational damage.
So, it is important to clear your name of any illegal cases. Since the sobriety tests are not accurate, you can challenge the results in court and prove yourself to be innocent.
And, to do that, a DUI lawyer can guide you through the process. So, you can take their help to clean up your name and bring back the reputation for your brand or business.
How Do DUI Lawyers Challenge Breathalyzer Results?
Breathalyzers are meant to measure blood alcohol concentration (BAC) from the amount of alcohol in your breath.
Although common, these devices tend to err. Here is how a DUI lawyer can dispute their results:
1. Questioning Calibration And Maintenance
The breathalyzers need to be frequently calibrated and effectively maintained in order to deliver accurate results.
If the device that was employed in the arrest was not maintained as per state regulations, the reading can be invalid.
Mistakes in protocol can be discovered by a Saskatchewan DUI lawyer who can seek maintenance logs and operator certifications.
2. Challenging Officer Training And Operation
Even a perfectly operating device can give faulty results if not handled in the proper way. DUI attorneys usually check if the arresting officer was well-trained and tested accordingly.
Any departures, i.e., failing to observe the subject for the minimum time before testing, can make the result inadmissible.
3. Examining Medical And Environmental Factors
Some medical conditions (acid reflux or diabetes) and the environment around (mouthwash or specific diets) may produce falsely increased BAC readings.
A DUI lawyer can call expert testimony or medical records to cast a reasonable doubt regarding the accuracy of the test.
How Do DUI Lawyers Challenge Field Sobriety Tests (FSTs)?
Field testing is a subjective test of a person’s physical and mental faculties conducted during a traffic stop.
Some of the common FSTs include the Horizontal Gaze Nystagmus, Walk-and-Turn, and One-Leg Stand. DUI lawyers will often claim the unreliability of using these tests to establish impairment.
1. Highlighting Subjective Interpretation
The sergeant felt that FSTs are unlike a breathalyzer, which is based more on one’s judgment of an officer.
A DUI lawyer can reveal inconsistencies in the report of the officer, body camera footage, or how tests were conducted.
In case the officer did not provide clear instructions or graded performance unfairly, the results can be disqualified.
2. Arguing Physical Or Medical Limitations
People with problems with balance, who are injured, have neurological conditions, or even anxiety, may face difficulty doing FSTs, independent of whether or not they include alcohol.
Your lawyer might use medical evidence or an expert’s opinion to suggest how these factors influenced your performance.
3. Questioning Road And Weather Conditions
If the road pavement is uneven or your surrounding of the test is dimly lit or you are distracted by traffic or unfavorable weather, field sobriety tests may be disadvantaged in any of such instances.
With the conditions not being perfect, a DUI attorney cites that the results were inherently not reliable.
Why Should You Get A DUI Lawyer?
However, Breathalyzer and field sobriety test results can be considered as iron-clad evidence, but they are not conclusive. A practiced DUI lawyer guides you through the sobriety tests.
And, they know how to question the effective conduct of these tests, reveal procedural flaws, and sow a seed of doubt, which can result in lessened charges or in case dismissal.
It is wrong to think that if you are facing DUI charges, the evidence against you is undefeatable. Contact a DUI defense attorney who can fight for your rights and your future.
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