Top 5 Defenses Against a DUI Charge

Top 5 Defenses Against a DUI Charge

Top 5 Defenses Against a DUI Charge

  1. Improper stop

Under the Fourth Amendment to the U.S. Constitution, every person is protected against unreasonable searches and seizures. In interpreting this amendment, the courts have held that before a police officer may pull over a vehicle, the police officer must have a “reasonable suspicion” that the driver is committing a crime. However, if the police officer merely has reasonable suspicion, and not probable cause, then the officer may not detain the individual, and the individual is free to leave at any time. In order to lawfully arrest anyone, the police officer must have probable cause to believe that the individual has committed a crime.

Because of this interpretation, the most common defense to a DUI charge is that the police officer did not have the requisite “reasonable suspicion” to pull over the individual charged, and/or the police officer did not have the requisite probable cause to justify a chemical test of the individual.

Arguing that the officer did not have the requisite reasonable suspicion to pull over someone can sometimes be a difficult argument. Since a police officer has the authority to pull over anyone for ANY traffic violation, even a slight violation will be enough to constitute reasonable suspicion sufficient to pull over the individual.

Probable cause, however, may be an easier argument since it requires a higher showing that there was actually a crime committed. When arresting an individual and requesting them to take a chemical test, police officers usually base their probable cause upon the person’s appearance and, if field sobriety tests are administered, their ability, or inability, to perform these tests. Some cues that police officers often look for include red and watery or glassy eyes, slurred speech, difficulty exiting the vehicle, inconsistencies in their statements, and a failing of the field sobriety tests.

  1. Field Sobriety Tests were administered inaccurately

Field sobriety tests are usually performed near where the individual was initially pulled over. The common field sobriety tests utilized are: the horizontal and vertical gaze nystagmus (HGN) test, the walk and turn test, and the one-legged stand test. The last two tests must be performed on dry, even surfaces in order to be accurate. Therefore, the accuracy of these tests may be challenged where the weather has been bad causing a wet surface, or where the surface is uneven or full of debris. The HGN test must be performed without flashing lights on the individual’s face. Therefore, if the officer forgets to turn off the emergency lights that are facing the individual, the accuracy of the test can be challenged.

Each test has a set protocol for how to properly perform each test, and if the officer varies at all from these protocols, the accuracy of these tests can be questioned, often successfully. Furthermore, if the officer has not been properly trained in administering these tests, the accuracy of the testing can be challenged.

  1. Breathalyzer machine was not maintained/was inaccurate

            If a breath test is administered, instead of a blood or urine test, then the individual may challenge the accuracy of the results. There are multiple ways to do this, however, the most common include challenging: the officer’s ability and training to use the machine, the accuracy of the test due to intervening factors, and the maintenance and calibration of the machine.

The first of these, challenging the officer’s ability and training to use the machine, is often a futile defense since police officers usually will not utilize a machine that they have not yet been trained on. However, it is an easy thing to check and see if the officer has received the requisite training, and if not, to challenge the accuracy of the test in court.

Intervening factors that could affect the accuracy of a breath test include whether the individual had previously been vomiting and whether the individual has indigestion. While both sides can produce experts to testify about this topic, there is some science that shows that indigestion within an individual can cause a breath test to produce a false positive for alcohol. While not all courts accept this argument, some courts are more receptive towards these types of arguments than others.

The best way to challenge the accuracy of a breath test is to introduce evidence that the machine was not properly maintained, or that the machine was not calibrated prior to utilizing it. Police stations will often keep maintenance records showing the last maintenance date of the machine, and these records can be requested by the defense. Therefore, if a machine has not received the required maintenance, the accuracy of the entire test can be called into question. 

  1. Chain of custody defense

This defense is only used when a blood test is administered to the individual charged, or when a substance was taken from the individual to be tested for the presence of drugs. When police officers take a blood sample, or seize evidence of drugs from the individual, they must take steps to insure that the sample/evidence is not contaminated and is not mislabeled. In order to do this, the sample/evidence usually will be sealed within labeled packaging and have a “chain of custody form” attached to the outside of the package. The chain of custody form must be filled out whenever a new person takes custody of the sample/evidence.

If the chain of custody form is missing, or if it appears the sample/evidence was somehow tampered with or contaminated, then the individual can claim that any results from the testing of the sample/evidence are unreliable and should not be allowed in court. If the prosecution cannot prove that the sample/evidence followed the proper chain of custody, then the court will usually suppress the best evidence the prosecution has to prove that the individual had alcohol or drugs in their system.

  1. Affirmative Defenses

Affirmative defenses are defenses that the person being charged must bring up in court and must offer evidence of the defense. The affirmative defenses available to a DUI defendant include: necessity, duress, entrapment, and involuntary intoxication.

The necessity defense arises whenever an individual chooses to drive while intoxicated in order to prevent a greater evil. In order for this defense to be successful, the person charged must provide enough evidence to show that they had no other option than to drive, and that the “greater evil” that was being avoided was more serious than the potential harm caused by driving under the influence.

Duress can be raised whenever an individual drives under the influence in order to avoid serious injury or death. The duress is usually caused by another person forcing the individual to drive by threatening that individual with serious injury or death.

Entrapment can be raised only in a very fact specific scenario. In order to be able to raise the entrapment defense, a police officer must be the person who tells, or requests, that the individual drive while intoxicated. Furthermore, the individual must also show that they were not “predisposed” to driving while intoxicated and would not have done so without the alleged entrapment by the police officer.

Involuntary intoxication can be raised by whenever an individual is given alcohol or drugs without their knowledge. For example, if an individual drinks from a punchbowl at a party that was “spiked,” without any evidence (including taste and smell) that the punch had alcohol in it, and the individual then drives, they can claim involuntary intoxication as a defense. This defense can be more difficult to prove when it comes to alcohol, since it is harder to prove that the individual had no reason to know that the drink they were consuming had any alcohol in it.


Please consult an attorney for advice about your individual situation. This site and its information is not legal advice, nor is it intended to be. Feel free to get in touch by electronic mail, letters, or phone calls. Contacting us does not create an attorney-client relationship. Until an attorney-client relationship is established, please withhold from sending any confidential information to us.


Tamara Shannon

3 years ago

I have to leave a comment regarding the 5 points you mention that the UHP has to follow, specifically the chain of custody. My husband was just convicted of a DUI after almost 4 years of fighting it after a single person motorcycle accident. The first responding officer testified that he did not smell alcohol but the second UHP officer that went to the hospital to just question dave, said he did after over 2 hours had gone by and then asked to draw blood and did so out of an IV catheter when he had been getting fluids and heavy pain mess such as fentanyl. He first testified that he out the blood in the mail and then the next trial said he logged it into the evidence locker. These lies are all on tape. The blood had no chain of custody filled out anywhere and no account for it for 9 days. The officer also testified that the nurse flushed the line for him but IHC. hospitals do not allow that. I work for them.. His blood was .13 but that was after IV contamination. Fentanyl is a synthetic opioid of morphine but stronger. It has ethanol in it. But again no chain of custody. The prosecutor stated that it doesn’t matter if the tape on the vials were not tampered with. I honestly don’t understand this and I am now changing my major to law. I really feel that the law is set up for you to fail. It seems chain of custody doesn’t matter and why even have a form for it if it is not followed. A jury if 4 convicted him and realistically the blood should have been thrown out. But the judge ruled for it to be admissible. My husband is paralyzed. From his accident. He will never be the same. There were no witnesses to it but yet he also got convicted of failure to stay in his lane. Which no one saw and is just a guess. This was our appeal and actually at the pre trial for this, the previous judge dismissed the hole case with prejudice because the prosecution could not produce an evidence locker officer to testify for chain of custody. How does this happen . my husband has never been in trouble and served this country for 24 years with 6 deployments. I plan on petitioning to some how make some noise to how your rights in Utah with DUI means nothing and is prejudice in itself.
Thank you

  • Call Now (801) 872-2222
    Free Case Review
  • This field is for validation purposes and should be left unchanged.

Test Ring Me

Client Reviews

Exceptional staff. Do everything to help you with your case. Would definitely recommend going here for your legal needsread more
Ryan Blake and Sherri Strong were so great to work with during my divorce. They were very responsive and understanding of my situation. I would highly reccommend using Hepworth and more
I love these guys, They do such a good job with all of my legal needs. They handle my business and family law. There strategies are top notch. Well done. And thank more
More than 100% confident in Michael and John. Both have represented me in business law. Never seen anything they can't more
I have full confidence in their abilities and expertise.
Mike was fast in responding to my situation. So far they have been great to respond to any and all questions. Will update more
My man was Tyler. He did an excellent job for me on all counts, his staff was very prompt to my inquiries. I always felt well taken care. I feel like i gained a friend😎read more
my fiancée had to call there office repeatedly to get the status of my case. My fiancée singlehandedly kept the case from getting dismissed because it had sat carelessly dormant for so long and it was her that had to bring it to there attention. And then, when we suggested a way for them to address the obstacles created by my ex-wife and the careless mishandling of my matter (I suggested filing a Motion to Waive the Requirement for Respondent to Take the Parenting Class), your office responded that it couldn’t be done, when in fact, I knew it could be. I paid a paralegal to draft a motion, forwarded it to you and then your office copied it in and submitted it to the court…then the magic happened. The case was resolved and the divorce was granted. I provided you with the legal fodder to complete the job. I was told my case flat-fee agreement (in flat fee cases , I understand that I will not be billed for phone calls, faxes, court appearances, attorney preparation time, paralegal time, or any other hourly fees for work done by the Firm.) than I got a bill 2 years later for 540.98 said they could not reach me... also never got any final paperwork from them... I also did upfront fee $1,300.00 and now its at collections ... I did turn them in to the Utah State more
When I started looking for a divorce lawyer I was nervous because I had been married for 20 years (2nd marriage). So I googled inexpensive divorce lawyers and guess what, your law firm came up first. Coincidence? Maybe because I normally would look further but I had a good feeling about this firm. Turns out I was right. Ben Lawrence got in touch with me he listened to my story gave me his advice went over costs and how it worked and I was hooked. He was very intelligent, knowledgeable, and willing to help me the whole way through the process. He was the best person/lawyer I could have ever found. And I went with my gut!! He is the best!!!read more
They are the best at what they do, very professional. I haven’t ever felt like just a client, I felt like they actually cared and tried as a great mentor when I was lost, willing to be their and give advice on a friendly level to. And although I wasn’t the easiest to deal with late on payment and keep wanting to hold off, Hepworth was always their on time to deal the best. Give it up for my man Ryan b he’s awsome and very fair. Hepworth is the way to go. Great service is what you can more
Hepworth & Associates is amazing!!!! I would recommend them to all of my family and friends. They did a great job at communicating with me through the whole process and made sure my case was handled quickly and professionally. Sonja was very knowledgeable and made me feel at ease through the whole process. She answered all of my questions very quickly and made sure I knew what to expect through the process. I am so grateful I went with Hepworth!read more
This was the first time I have ever experienced any situation were I needed legal help! Mike and John were more help then I ever expected. They answered any and every question the first time even if it was the same question over and over again. I never felt like I was bothering any of them! I would use them in the future and highly recommend this office!!!read more
I used Micheal to get out of a commercial lease, he saved me $10,000 a month plus help me get money back from a former business partner that strapped me with an additional $42,000 in debt. Thanks Michael Hepworth really appreciate the more
yes!! they saved me. I was being sued.they were wonderful and quickly got the other party to drop the case that should never have been started. they let us make payments on the lawyer fees. tyread more
Fast response. Willing to answer any and all questions and gets back with you quick. I will be adding more to this review as time goes more
I called just to see if anything could be done for my situation. They had an easy form for me to fill out for the attorney to review before deciding if I should come in for a free consultation. It was so easy and the secretary was very professional and kind. Even if I don't have a case, I will definitely be contacting them in the future if the need more
These guys are excellent attorneys and have a great staff! I highly recommend them!
I was facing a powerful multibiollion dollar corporation in a law suit! Me Hepworth and his associates did an outstanding job in representing me! I am so pleased with my representation! They kept me informed the entire time! They were sensitive to my concerns! They helped me get a very good settlement!If you want a bulldog attorney on your side, I can’t give you a better recommendation than Michael Hepworth and associates!read more
They were a godsend for me. I had looked for an attorney to help me for several years and they were the best. I won a difficult case dealing with homeowners more
I just wanna say a HUGGEEE thank you to Chelsea and Michael Hepworth in helping me getting my case dismissed!!!!! not only was Michael patient and understood my situation but he also made sure i wasn’t railroaded at the end of the day!! Chelsea did such a great job in gathering my information together and help me with my pay plan! I had to pay excessive fees for my impound fees and was short on funds and she completely understand where i was coming from! i recommend these guys to you not only are they SHARP but they get it down, my case is now dismissed COMPLETELY!! thank you Hepworth & Associates!!!read more

Search Site

Generic selectors
Exact matches only
Search in title
Search in content
Search in posts
Search in pages
Filter by Categories
Accident and Injury
Business Law
Car Accidents
Child Custody
Child Support
Civil Law
Constitutional Law
Contract Law
Corporate Law
Criminal Defense
Criminal Law
DUI Defense
Employment Law
Eviction Law
Family Law
Father's Rights
Landlord Tenant Law
Mother's Rights
Personal Injury
Protective Orders
Real Estate Law
Trials & Litigation
Trusts, Wills & Estate Planning
Wills & Estate Planning
Wills & Trusts