Medical defense in OUI/DUI cases

Medical evidence can assist in defending your Massachusetts OUI arrest. Your medical condition may impact the reliability of the breathalyzer test, the conclusion of the officer as to how you performed on the field sobriety tests and could help to explain observations of the officer that the officer attributes to being under the influence of alcohol.

  • Field Sobriety tests and Medical Evidence.

    Medical defenses would include evidence of an injury to either your knees:

    • Knees
    • Back
    • Or legs that would impact balance as field sobriety tests are essentially balance and coordination exercises.

  • How evidence can this evidence be presented at trial? There are 3 ways to present medical evidence relating to your performance on field sobriety tests:

    • Testimony from treating doctor
    • Testimony in the form of a sworn medical affidavit;
    • Through your own testimony explaining the injury or the testimony of someone with knowledge of your injury.
  • An injury could explain an officer’s observations of lack of balance or being unsteady while walking. When you have a medical condition unknown to the officer, a strong argument can be made that the officer could not accurately access your performance without knowing your medical condition and physical limitations.

  • Impact of a medical condition at a breathalyzer refusal appeal:

    Medical evidence can also be used at a breathalyzer refusal appeal. This may occur when an individual has a lower lung capacity or trouble breathing into the machine; in many cases, the officer may attempt to deem this as a refusal of the breath test when a medical condition explains the inability to provide a breath sample. Medical evidence could be offered to contradict the claim that the motorist refused the breathalyzer. This evidence can be presented at the Registry of Motor Vehicles to challenge a license suspension for refusing a breathalyzer test.

Medical Evidence that may undermine the accuracy of breathalyzer test results:

  • Medical conditions can also impact the results of breathalyzer testing:
    • Since the accuracy of the breathalyzer machine is dependent on the assumption that the motorist is the normal or average individual, medical conditions sometimes undermine the assumptions made by the breathalyzer machine. Below is a list of some medical conditions that can impact the results of the breath test.


  • Being a diabetic can influence the results of the breathalyzer:
    • When a diabetic is in a state of ketoacidosis, the diabetic’s blood sugar raises as the body is unable to use carbohydrates as a source of fuel and burns stored fat as fuel and produces ketones
    • A breathalyzer machine may wrongful detect ketones as ethyl alcohol and provide a blood alcohol reading that is falsely elevated


  • Acid Reflux can impact the breathalyzer test results as alcohol from the stomach is reintroduced into the throat and mouth:
    • When a breathalyzer sample is taken, the breathalyzer machine assumes that the sample being measured is deep lung air
    • The following conditions can cause alcohol in the stomach to rise up into the esophagus and lungs where it can cause a breathalyzer reading to give an artificially high result:
      • Acid Reflux
      • Burping
      • Belching
      • Regurgitating
      • Hiccups


  • Breathalyzer testing machines are nonspecific for alcohol
    • They do not test specifically for ethanol
    • There are many industrial compounds that contain a molecular structure similar to ethyl alcohol that a breathalyzer machine mistakes as alcohol.
    • One such substance is Toluene
      • Toluene can be found in industrial compounds such as paint thinner, cleaning agents and industrial products
    • Studies have shown that these industrial compounds can be registered as alcohol by breathalyzer machines.
      • Carpenters, plumbers, janitors and other manual labors may have been exposed to these compounds, causing an artificially high breathalyzer reading.

To Learn more about medical conditions that may be relevant to defending your Massachusetts OUI charge, you can download Attorney DelSignore free book or you may call to ask your questions directly at 781-686-5924.

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