Arizona DUI Defenses





It is important to understand that there are many ways to defend DUI charges. When Todd K. Coolidge prepares a DUI defense there are a number of constitutional and statutory challenges that he looks for. Some of those include:


  • No Reasonable Suspicion to Stop:
    In order for an officer to stop a vehicle for suspected DUI, the officer can only make the stop if there is a traffic violation, or facts to support an articulable reasonable suspicion of criminal activity. Todd K. Coolidge will file a motion to suppress if there was no reason for the officer to make the stop. If the Court determines that there was no reasonable suspicion for the stop, all evidence gathered after the stop will be suppressed.
  • No Probable Cause to Arrest:
    An officer must have probable cause in order to arrest an individual for DUI. If the officer does not have objective facts indicative of alcohol or drug impairment at the time of the arrest, Todd K. Coolidge will file a motion to suppress. If the Court agrees, all evidence gathered after the arrest must be suppressed.
  • Violation of Miranda Rights
    Once an officer arrests an individual for DUI, they cannot question them without explaining the individual’s rights under Miranda. If it is determined that the officer gained evidence in violation of Miranda, those statements can be suppressed.
  • Violation of the Right to Counsel:
    Once an individual has been arrested for DUI, that person has the right to speak with an attorney prior to deciding whether to submit to a blood breath or urine test as long as it does not interfere with the officer’s investigation. If an officer interferes with an individual’s right to speak with an attorney, the DUI can be dismissed or the blood breath or urine test can be suppressed. If you are arrested for DUI, Todd K. Coolidge is available 24/7 to take calls from the jail or DUI van.
  • Denial of the ability to gather exculpatory evidence (Independent Test):
    In all DUI cases, the main evidence used by the State to gain a conviction is the alcohol or drugs inside that person’s body. That evidence is being destroyed as time progresses. For that reason, all people arrested for DUI have a due process right to gather their own independent evidence. This includes being released to get an independent blood or urine test, taking photos of an accident scene, having someone record how the person walks or talks, or getting one’s temperature taken. If an officer interferes with this right, the DUI can be dismissed or evidence of the chemical test can be suppressed.
  • No Actual Physical Control (APC) of Vehicle:
    In Arizona, a person can be arrested for DUI even if they were not driving a motor vehicle. If the officer can show evidence that the person was in “actual physical control” of a vehicle, they can still be convicted of DUI. It is important to hire an attorney who is familiar with the law in order to show that they have relinquished control of the vehicle. Todd K. Coolidge is a Certified Criminal Law Specialist who is familiar with the law in the area of actual physical control.
  • No Corpus Delicti:
    Corpus Delicti is the doctrine of law that means that the State needs something more than a person’s statement or admission in order to obtain a conviction. In a DUI, the crime is committed when a person “drives” or is in “actual physical control” of a vehicle. Corpus Delicti typically arises in a DUI when there is an accident and there are no witnesses to who was driving the vehicle. The State needs something more than the person’s statement in order to convict.
  • Blood breath or urine test taken outside 2 hours:


Arizona’s DUI law indicates that it is illegal to drive with an illegal alcohol concentration or with drugs in a person’s body within 2 hours of driving. This means that officers are going to try and get a chemical test within that 2 hour window. If the officer fails to do so, the State will have to bring in an expert witness to indicate that the alcohol concentration would still have been above the legal limit within that 2 hour window. That expert would have to testify to a retrograde extrapolation.


This retrograde extrapolation is based on a person’s drinking history, time of driving, time of chemical test, and a number of other factors. This is usually based on the expert making a number of assumptions about the person charged with DUI. This retrograde extrapolation can be called into question and the chemical results possibly suppressed if the State has not proved the results beyond a reasonable doubt. This can also be used in order to prove someone is below the legal limit at the time of driving in an impairment case.


  • Intoxilyzer or Gas Chromatograph issues:
    The main piece of evidence used by the State during a DUI case is the chemical test. A breath test is usually administered using an Intoxilyzer. The blood test is usually conducted on a Gas Chromatograph.

Both of these types of tests are conducted using a machine. There are a number of rules and regulations that govern the use of these machines. There are also a number of factors that can affect the results these machines produce.

Some of the errors associated with an Intoxilyzer (breath) test are:

Range of Error
Variables for the instrument, such as breath patterns, body temperature of the accused, and blood to breath partition ratio
Operator Error
Mouth alcohol
Radio frequency interference


The Intoxilyzer is a machine that has to be calibrated every 30 days, and tested every 90 days to make sure it can catch some of the issues listed above. A thorough investigation of the calibration records and standard quality assurance records is necessary in order to show that the machine is functioning properly and accurately.


Some of the errors associated with a Gas Chromatograph are:


  • Contamination of Blood
  • Phlebotomist Error (Human Error):
  • Blood analyst Error (Human Error):
  • Headspace Gas Chromatography Function Problems: