How a DUI Attorney Challenges Breathalyzer and Field Tests
- Meason & Morris Law
- Jun 29
- 12 min read
Have you or someone you know been pulled over for driving under the influence? If so, you might feel scared and confused. You might think that because you took a breathalyzer test or a field sobriety test, you are automatically guilty. But that is simply not true! A good DUI Attorney knows that these tests are not perfect. In fact, they can be very wrong. At Meason & Morris Law, we help people fight unfair DUI charges. We know exactly how to challenge breathalyzer and field test results.
In this article, we will explain how a DUI Attorney can challenge these tests. We will talk about why breathalyzers make mistakes. We will also look at why field sobriety tests are not always fair. If you want to protect your rights, keep reading. You will learn how the right lawyer can make a big difference in your case.
What is a Breathalyzer Test?
A breathalyzer is a machine that police officers use. They use it to measure how much alcohol is in your breath. This number is called your Blood Alcohol Concentration, or BAC . In most places, if your BAC is 0.08% or higher, you can be charged with a DUI.
Police officers use small breathalyzers on the side of the road. They also use bigger machines at the police station. The police and the courts often act like these machines are always right. But they are not. These machines are just tools. Like any tool, they can break. They can be used the wrong way. A smart DUI Attorney knows how to find these mistakes.
Why Breathalyzers Make Mistakes
You might wonder how a fancy machine can be wrong. There are actually many reasons. A DUI Attorney will look at all of them to build your defense. Here are some of the most common reasons why breathalyzers give false results.
The Machine Was Not Calibrated
A breathalyzer is a sensitive machine. It needs to be checked and fixed often. This is called calibration . If the police do not calibrate the machine, it will not work right. It might say your BAC is high when it is really low.
A DUI Attorney will ask the police for the maintenance records of the machine. These records show when the machine was checked. If the police missed a check-up, your lawyer can tell the judge. The judge might say the test results cannot be used against you.
The Officer Did Not Follow the Rules
Police officers must follow strict rules when they give a breath test. For example, they usually have to watch you for 15 minutes before the test . This is to make sure you do not burp, throw up, or put anything in your mouth. If you do these things, it can put more alcohol in your mouth. This makes the machine think you are drunker than you are.
If the officer did not watch you for 15 minutes, the test might be wrong. Your DUI Attorney will ask the officer questions about this. If the officer broke the rules, your lawyer can fight the test results.
Medical Conditions
Sometimes, your own body can trick the breathalyzer. Certain medical conditions can make your breath seem like it has alcohol in it, even if you have not been drinking.
For example, if you have acid reflux or heartburn, stomach acid can come up into your throat. This acid can confuse the machine. Diabetes can also cause problems. People with diabetes sometimes have ketones in their breath. The breathalyzer might think these ketones are alcohol . A good DUI Attorney will use your medical records to show why the test was wrong.
Your Diet
Did you know that what you eat can affect a breath test? If you are on a low-carb diet, like the Keto diet, your body makes ketones . Just like with diabetes, the machine can mistake these ketones for alcohol. Your lawyer can explain this to the court.
Mouth Alcohol
Breathalyzers are supposed to measure the air deep in your lungs. But sometimes, they measure the air in your mouth instead. This is called "mouth alcohol".
Mouth alcohol can come from many things. If you just used mouthwash, your breath might have alcohol in it. Cough syrup can do this, too. Even burping can bring alcohol from your stomach into your mouth. If the machine measures mouth alcohol, the result will be too high. A DUI Attorney knows how to prove that mouth alcohol ruined the test.
What Are Field Sobriety Tests?
Besides the breathalyzer, police officers often use field sobriety tests. These are physical tests they make you do on the side of the road. They want to see if you can balance and follow directions. If you mess up, they will say you are drunk.
There are three main tests that most police use:
The Horizontal Gaze Nystagmus (HGN) Test:
The officer tells you to follow a pen or a light with your eyes. They are looking for your eyes to jerk.
The Walk-and-Turn Test:
The officer tells you to walk in a straight line, heel-to-toe, and then turn around.
The One-Leg Stand Test:
The officer tells you to stand on one leg and count out loud.
These tests sound simple, but they are very hard to do perfectly. Even sober people fail them all the time. A DUI Attorney knows how to challenge these tests in court.
Why Field Sobriety Tests Are Unfair
Field sobriety tests are not based on perfect science. They are just a way for the officer to guess if you are drunk. Here is how a DUI Attorney can show that these tests are unfair.
The Tests Are Hard for Anyone
Think about standing on one leg on the side of a busy road at night. Cars are zooming by. The police car lights are flashing in your eyes. You are scared and nervous. It is very hard to balance in this situation!
Many people cannot do the Walk-and-Turn or the One-Leg Stand even when they are completely sober . If you are tired, nervous, or clumsy, you might fail. Your lawyer will explain to the jury that failing these tests does not mean you were drunk. It just means you are
human.
The Officer Graded You Unfairly
The police officer is the one who decides if you pass or fail. But officers are not perfect. Sometimes they are biased. They might decide you are drunk before you even start the test .
If you put your foot down for one second, the officer might fail you. If you start the test before they say "go," they might fail you. A DUI Attorney will watch the video of your arrest. They will look for times when the officer was too harsh or made a mistake in grading you.
Medical and Physical Problems
Just like with the breathalyzer, your body can make it hard to pass field sobriety tests. If you have a bad back, bad knees, or inner ear problems, you might not be able to balance. If you are overweight or older, these tests are much harder.
Even your eyes can trick the officer. In the HGN test, the officer looks for your eyes to jerk. But many things can cause this, not just alcohol. Brain injuries, certain medicines, and even being very tired can make your eyes jerk . Your DUI Attorney will use your medical history to show why you could not pass the tests.
Bad Weather and Bad Roads
The place where you take the test matters a lot. If the road is bumpy or slanted, it is hard to walk in a straight line. If it is raining, snowing, or very windy, it is hard to balance . If the officer made you take the test in a bad spot, your lawyer can use that to challenge the results.
What You Were Wearing
Believe it or not, your shoes can make you fail a field sobriety test. If you are wearing high heels, cowboy boots, or flip-flops, it is almost impossible to walk heel-to-toe . If you were wearing clothes that made it hard to move, your lawyer will point that out to the judge.
How a DUI Attorney Fights for You
Now you know that breathalyzers and field sobriety tests are not perfect. But how does a DUI Attorney actually use this information to help you? Here are the steps a lawyer at Meason & Morris Law will take.
1. Investigating the Arrest
The first thing your lawyer will do is look at everything that happened when you were arrested. They will read the police report. They will watch the video from the police car and the officer's body camera. They want to see exactly how the officer treated you. Did the officer follow the rules? Did they make mistakes? The video often shows the truth.
2. Getting the Records
Your DUI Attorney will demand all the records for the breathalyzer machine. They will look at the maintenance logs. They will check to see if the machine was calibrated correctly. If the records are missing or show problems, your lawyer has strong evidence to help you.
3. Using Expert Witnesses
Sometimes, your lawyer will bring in an expert to help with your case. This expert might be a scientist or a doctor. The expert can explain to the judge and jury why the breathalyzer or the field tests were wrong . For example, a doctor can explain how your acid reflux caused a false breathalyzer reading. An expert can make your defense much stronger.
4. Filing Motions to Suppress
If the police broke the rules, your lawyer can file a "Motion to Suppress." This is a request to the judge. The lawyer asks the judge to throw out the test results.
For example, if the officer did not have a good reason to pull you over in the first place, the whole arrest might be illegal. If the judge agrees, the breathalyzer and field test results cannot be used in court. Without those results, the prosecutor might have to drop the charges against you.
5. Negotiating with the Prosecutor
Most DUI cases do not go to trial. Instead, the lawyer talks to the prosecutor. The prosecutor is the lawyer for the government. If your DUI Attorney can show that the test results are weak, the prosecutor might be willing to make a deal.
They might agree to lower the charges. For example, instead of a DUI, you might get a ticket for reckless driving. Or, they might agree to a lighter punishment, like taking a class instead of going to jail. A strong defense gives you a better chance at a good deal.
6. Fighting in Court
If the prosecutor will not make a fair deal, your DUI Attorney will fight for you in a trial. In a trial, the jury gets to decide if you are guilty. Your lawyer will show the jury all the problems with the breathalyzer and the field tests. They will explain that the machines make mistakes and the tests are unfair. The goal is to show the jury that there is "reasonable doubt." If the jury has reasonable doubt, they must say you are not guilty .
Why You Need Meason & Morris Law
Facing a DUI charge is serious. A conviction can cost you a lot of money. You could lose your driver's license. You could even go to jail. It can also hurt your job and your reputation. You should not try to fight this alone.
You need a DUI Attorney who knows how to challenge the evidence against you. At Meason & Morris Law, we have the experience and the knowledge to help you. We know the science behind the breathalyzers. We know the rules the police are supposed to follow. We know how to find their mistakes.
When you hire Meason & Morris Law, we will treat you with respect. We will listen to your story. We will work hard to build the best defense for you. We will fight to protect your rights, your license, and your future.
What to Do If You Are Pulled Over
If you are ever pulled over for a DUI, it is important to know your rights. Here are a few tips on what to do:
• Be Polite:
Always be polite to the police officer. Do not argue or get angry.
• Stay Quiet:
You do not have to answer all of the officer's questions. You have the right to remain silent. You can just say, "I would like to speak to my attorney."
• Think Before You Test:
In many places, you can refuse to take the field sobriety tests. You might also be able to refuse the roadside breath test (the small machine). However, refusing the big breath test at the station might lead to losing your license. It is a tough choice, but remember that these tests are designed to make you look guilty.
• Call a Lawyer Fast:
As soon as you can, call a DUI Attorney. The sooner you get a lawyer, the better they can help you.
Understanding the Details: A Closer Look at the Science
To really understand how a DUI Attorney challenges these tests, it helps to look a little closer at the science. Let's talk more about how the breathalyzer actually works and why it gets confused.
The most common breathalyzers use something called infrared spectroscopy. This means the machine shines an infrared light through the breath sample. Alcohol absorbs this light in a specific way. The machine measures how much light is absorbed to guess how much alcohol is there.
But here is the problem: alcohol is not the only thing that absorbs infrared light. There are thousands of other chemical compounds that look just like alcohol to the machine. These are called "interferents."
For example, the chemical group called "methyl" looks very similar to the "ethyl" group in drinking alcohol. Methyl compounds are found in many everyday things, like paint thinner, glue, and even some foods. If you work around these chemicals, or if you just ate something with them, the machine might read them as alcohol.
A smart DUI Attorney will ask you about your job, your hobbies, and what you ate that day. They will look for any reason why an interferent might have tricked the machine.
The Problem with Averages
Another big problem with breathalyzers is that they rely on averages. The machine assumes that everyone's body works exactly the same way. But we know that is not true!
To figure out your Blood Alcohol Concentration (BAC), the machine measures the alcohol in your breath and then multiplies it by a number called a "partition ratio." The standard partition ratio is 2100 to 1. This means the machine assumes there is 2100 times more alcohol in your blood than in your breath.
But scientists have proven that this ratio is not the same for everyone. Some people have a ratio of 1300 to 1. Some people have a ratio of 3000 to 1. Your ratio can even change depending on your body temperature or how fast you are breathing.
If your personal partition ratio is lower than 2100 to 1, the breathalyzer will say your BAC is much higher than it really is. A DUI Attorney can explain this complicated science to the jury. They can show that the machine's "one size fits all" math is unfair to you.
The Timing of the Test
Timing is everything in a DUI case. The law says it is illegal to drive with a BAC over the limit. It does not say it is illegal to have a high BAC at the police station an hour later.
When you drink alcohol, it takes time for your body to absorb it. If you have a drink right before you drive, your BAC might be very low while you are behind the wheel. But by the time the police pull you over, arrest you, and take you to the station, your body has absorbed more alcohol. Your BAC has gone up.
This is called "rising blood alcohol" . A DUI Attorney can argue that your BAC was under the limit when you were actually driving. They can use the timeline of your night to show that the test at the station does not prove you were driving drunk.
Challenging the Officer's Opinion
When it comes to field sobriety tests, the biggest problem is that they rely on the officer's opinion. The officer is not a doctor or a scientist. They are just a person making a guess.
During the trial, your DUI Attorney will cross-examine the officer. This means the lawyer gets to ask the officer tough questions. The lawyer will ask the officer about their training. They will ask exactly how the tests are supposed to be done.
Often, the lawyer can get the officer to admit that they made a mistake. For example, the lawyer might ask, "Isn't it true that you didn't tell my client they could take off their high heels before the walk-and-turn test?" If the officer says yes, the jury will see that the test was not fair.
The lawyer will also point out all the things you did right. The officer's report will only list the things you did wrong. But the lawyer will ask, "Didn't my client pull over safely? Didn't they hand you their license without fumbling? Didn't they speak clearly?" Showing the jury that you acted sober in many ways can create reasonable doubt.
Your Rights Matter
The most important thing to remember is that you have rights. The Constitution protects you from unfair searches and false evidence. A breathalyzer test is a type of search. If the test is flawed, it is a violation of your rights.
A DUI Attorney is your shield against the power of the government. They make sure the police and the courts follow the rules. They make sure you get a fair fight.
Conclusion
A DUI charge can feel like the end of the world, but it does not have to be. Just because a machine or an officer says you were drunk does not mean it is true. Breathalyzers break down and make mistakes. Field sobriety tests are hard and unfair.
A skilled DUI Attorney knows how to expose these problems. They know how to challenge the results and fight for your freedom. If you are facing a DUI, do not give up hope. Contact Meason & Morris Law today. Let us review your case and show you how we can help. We will stand by your side and fight for the best possible outcome.
Remember, the evidence against you might look strong, but a good lawyer knows where to look for the cracks. Do not let a flawed test ruin your life. Let a DUI Attorney from Meason & Morris Law challenge the results and protect your rights.
Meason & Morris Law is a legal firm led by seasoned attorneys Marty Meason and Chris Morris. We provide a professional experience for all our clients, helping them navigate their legal rights. We focus on Criminal Justice Law (felonies and misdemeanors), Divorce and Family Law, Expungement and Felony Law, Probate Law and also have Trial experience. Serving Washington County, Nowata County, Osage County, Rogers County, Payne County, Pawnee County, and Kay County in Oklahoma.
Meason & Morris Law
515 Delaware Ave
Bartlesville, OK 74003
918-336-6300
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