Summary of Drunk Driving (DUI) Defenses

Below are only a few examples of possible defenses that could be used in a drunk or impaired driving case. A specialized DUI attorney will know and understand many other ways to recognize DUI defenses and challenge the legal aspects of each case. This list should not be used as limiting defenses for every DUI-DWI charge.

1. 1. Defenses related to the legality or sufficiency of the complaint, information, or other charging instruments.
      • • The form or type of instrument used does not comply with the applicable statute or rule.
        • The instrument does not adequately or specifically inform the defendant of the offense of which he or she is charged.
        • The instrument fails to allege the necessary jurisdictional facts or venue requirements.
        • The instrument fails to allege a violation of the law.
        • The instrument was not properly signed or notarized.
        • The instrument was not filed in the proper court within the required period.

      * Note: If any of these defenses can be established, the case is subject to dismissal, unless the prosecutor is permitted to amend the charging instrument.

   2. Defenses related to the legality of a roadblock or the stop of the defendant’s vehicle.
      • • The defendant was stopped by the police at an illegal roadblock.
        • The officer did not have an articulable suspicion of illegal activity at the time of the stop.
        • The stop of the defendant was based on an uncorroborated tip from an unidentified informant.

      * Note: If any of these defenses can be established, all evidence acquired as a result of the stop will be inadmissible.

   3. Defenses related to the arrest of the defendant.
      • • At the time of the arrest, the officer did not have “probable cause” to believe that the defendant had committed each element of the charged offense.
        • The officer failed to obtain a warrant before arresting the defendant and – (i) the defendant was arrested in his or her home, or (ii) the offense was not committed in the presence of the officer and local law requires a warrant under such circumstances.
        • The officer had no authority to arrest the defendant because the arrest occurred outside of the officer’s jurisdiction.

      * Note: If an unlawful arrest can be established, any evidence obtained as a result of the arrest, including chemical test evidence, will be inadmissible.

   4. Defenses related to an unlawful search and seizure.
      • • A warrantless search of the defendant or the defendant’s vehicle or property was conducted that was not incidental to a lawful arrest.
        • A defective search warrant was used to search the defendant’s premises or property.

      * Note: If an unlawful search and seizure can be established, any evidence obtained as a result thereof will be inadmissible.

   5. Defenses related to the violation by the police of the defendant’s Fifth Amendment privilege against self-incrimination.
      • • The police failed to give the defendant a timely and adequate “Miranda warning.”
        • After the giving of a valid Miranda warning, the police obtained statements or other testimonial evidence from the defendant in violation of the defendant’s Fifth Amendment privilege against self-incrimination.

      * Note: If a Miranda warning was required and was not given, any statements made by the defendant to the police subsequent to when the warning should have been given are inadmissible. Any statements of the defendant obtained by the police in violation of the defendant’s Fifth Amendment privilege against self-incrimination after the giving of a Miranda warning are also inadmissible.

   6. Defenses related to the violation by the police of the defendant’s constitutional or statutory right to counsel.
      • • The police failed to timely and adequately advise the defendant of his or her right to counsel.
        • After advising the defendant of his or her right to counsel, the police obtained statements or physical evidence from the defendant in violation of the defendant’s constitutional or statutory right to counsel.

      * Note: If the police failed to advise the defendant of the right to counsel when the right is attached, any statements or physical evidence (including chemical test evidence) thereafter obtained from the defendant by the police is inadmissible. Any statements or physical evidence obtained by the police from the defendant in violation of the defendant’s constitutional or statutory right to counsel after advising the defendant of the right are also generally inadmissible.

   7. Defenses related to the failure of the police to comply with the requirements of the local implied consent statute.
      • • The police officer failed to lawfully arrest the defendant prior to requesting chemical testing, and a lawful arrest is required under local law as a condition to chemical testing.
        • The police officer did not have reasonable grounds to believe that the defendant had committed a drinking-driving offense when chemical testing was requested, and such grounds are required under local law.
        • The police officer failed to advise the defendant of the consequences of refusing to be tested, and such advisement is required under local law.
        • The police officer failed to advise the defendant of the consequences of submitting to testing, and such advisement is required under local law.
        • The police officer failed to advise the defendant of the alternate types of chemical tests to which the defendant could have chosen to submit, and such advisement is required under local law.
        • The police officer, in violation of local law, failed to permit the defendant to consult with an attorney prior to deciding whether to submit to chemical testing.

      * Note: If the police officer failed to perform a duty required under the local implied consent statute, the prosecution’s chemical test evidence (or the defendant’s refusal to submit to testing) may be inadmissible

   8. Defenses related to the failure of the police to comply with the requirements of the local independent test statute.
      • • The police officer failed to advise the defendant of the right to obtain an independent chemical test, and such advisement is required under local law.
        • The police officer, in violation of local law, interfered with the defendant’s attempt to obtain an independent chemical test.
        • The police officer, in violation of local law, failed to give the defendant a reasonable opportunity to obtain an independent chemical test.

      * Note: If a police officer violates a duty required under the local independent test statute, the prosecution’s chemical test evidence may be inadmissible.

   9. Defenses related to the prosecution’s ability to prove the elements of the offense, other than intoxication.
      • • It cannot be proven that the defendant “operated,” “drove” or “had actual physical control of” a vehicle while intoxicated.
        • It cannot be proven that the defendant operated a “motor vehicle,” as that term is defined locally.
        • It cannot be proven that the defendant operated a vehicle in a “location” that is covered under the local drinking-driving statute.

      * Note: The prosecution must prove each of these elements beyond a reasonable doubt in order to convict the defendant.

   10. Defenses related to the prosecution’s ability to prove the required degree of intoxication other than by chemical testing.
       • • There are exculpatory aspects of the police officer’s testimony, including a favorable observation of driving by the defendant prior to the stop and a favorable observation of the performance of certain field sobriety tests by the defendant.
         • There is videotape evidence in the hands of the police that is favorable to the defendant.
         • There are errors or inconsistencies in the reports or other written documents prepared by the police.
         • There are exculpatory oral or written statements made to the police by the defendant or by a prosecution witness.
         • There are defense witnesses who will give favorable testimony on the issue of the defendant’s sobriety.

       * Note: Exculpatory evidence in the hands of the police is discoverable by the defendant.

   11. Defenses related to the admissibility of the prosecution’s breath testing evidence.
       • • The breath test was not performed within a reasonable period after the commission of the alleged offense.
         • The breath testing instrument used on the defendant had not been approved or certified by the appropriate state agency or officer.
         • The breath testing instrument was not in proper working order when the defendant was tested.
         • The breath testing instrument had not been timely calibrated, inspected, or tested by a person certified or qualified to do so.
         • The operator of the breath testing instrument was not properly qualified or certified.
         • The operator of the breath testing instrument did not follow the required procedures in administering the defendant’s breath test.

       * Note: If any of the above defenses can be established, the prosecution may be unable to establish a foundation for the admissibility of the breath test result and it may be inadmissible.

   12. Defenses related to the credibility of the prosecution’s breath testing evidence.
       • • The amount of time that elapsed between the commission of the alleged offense and the performance of the breath test rendered the test result unreliable and inaccurate as an indicator of the defendant’s BAC at the time of the offense.
         • The defendant’s blood-breath alcohol partition ratio was, or may have been, lower than the 2100:1 ratio assumed by the breath testing instrument, and the test result may have been falsely high (i.e., the defense of a lower partition ratio).
         • The breath test was performed while the defendant was in the absorptive phase of the alcohol distribution process, and the BAC reported by the testing instrument was therefore falsely high and the defendant’s BAC at the time of testing was higher than at the time of driving (i.e., the defense of testing during absorption and the rising BAC defense).
         • The breath sample tested was, or may have been, contaminated by mouth alcohol, stomach alcohol or gases, non-consumed alcohol, endogenous bodily substances or inhaled substances, any of which could have caused a falsely high test result to have been reported by the breath testing instrument (i.e., defenses related to the integrity of the breath sample).
         • The breath-alcohol simulator used to check or calibrate the breath testing instrument produced inaccurate concentrations of alcohol, or the simulator test was incorrectly performed by an uncertified or unqualified person (i.e., defenses related to the simulator test error).
         • The breath testing instrument used was susceptible to radio frequency interference.
         • The breath test result was inconsistent with the amount of alcohol actually consumed by the defendant and with the defendant’s physical and mental abilities at the time of the offense.
         • The breath test result is inconsistent with the BAC indicated by an independent chemical test performed at the request of the defendant.
         • The defendant consumed alcohol between the end of driving and the time of testing, which rendered the test result unreliable as an indicator of the defendant’s BAC at the time of driving.

       * Note: The above defenses usually go to the credibility of the breath test result, and not to its admissibility. These defenses may be used to discredit an incriminating breath test result in the eyes of the jury.

   13. Defenses related to the admissibility of the prosecution’s blood testing evidence.
       • • The blood sample was not obtained within a reasonable period after the commission of the alleged offense.
         • The person who withdrew the blood sample was not legally qualified to do so.
         • The chain of identification and custody of the blood sample from the time of withdrawal to the time of testing cannot be established by the prosecution.
         • The method used to test the defendant’s blood has not been approved by the appropriate state agency or officer or is not considered to be scientifically reliable.
         • The person who performed the chemical test had not been certified or approved by the appropriate state agency or officer or was not professionally qualified to perform the test.
         • The chemical test was not performed in accordance with administratively-required practices or standards, or in accordance with scientifically accepted standards.

       * Note: If any of the above defenses can be established, the prosecution will be unable to establish a foundation for the blood test result and it will be inadmissible.

   14. Defenses related to the credibility of the prosecution’s blood testing evidence.
       • • The blood sample was not properly withdrawn, labeled, and preserved.
         • The blood sample withdrawn was not representative of the blood needed for an accurate chemical test (i.e., arterial blood was withdrawn, the sample was withdrawn during the absorptive phase of the alcohol distribution process, etc.).
         • The integrity of the blood sample was not maintained through the completion of chemical testing.
         • The chemical test was not accurately performed.
         • A duplicate or replicate test was not performed and an undetected random error could have occurred in the testing process.
         • Precautions were not taken to detect the presence of systematic error in the laboratory where the defendant’s blood sample was chemically tested.
         • The blood test result is inconsistent with the amount of alcohol actually consumed by the defendant and with the defendant’s physical and mental abilities at the time of the offense.
         • The test result is inconsistent with the BAC indicated by an independent chemical test performed at the request of the defendant.

       * Note: The above defenses, usually go to the credibility of a blood test result, and not to its admissibility. These defenses may be used to discredit an incriminating blood test results in the eyes of the jury.

   15. Defenses related to police misconduct.
       • • The police intentionally or in bad faith destroyed potentially exculpatory evidence.
         • The police negligently destroyed or failed to preserve potentially exculpatory evidence.
         • The police were required under local law to preserve a sample of the defendant’s blood, breath, or urine and failed to do so.

       * Note: If the intentional or bad-faith destruction of evidence by the police can be proven, the case is subject to dismissal. Otherwise the remedy for destroying or failing to preserve evidence is the exclusion of the prosecution’s evidence, including chemical test evidence.

   16. The defense of an unconstitutional or invalidly-adopted drinking-driving statute or ordinance.
       * Note: If this defense can be established, the case is subject to dismissal.

1. Defenses related to double jeopardy or collateral estoppel.
   • • The defendant was previously convicted or acquitted of an offense that is a lesser included offense of the present offense.
     • The defendant was previously convicted or acquitted of an offense of which the present offense is a lesser included offense.
     • The defendant was previously charged with the present offense and jeopardy attached in the prior proceeding.
     • An issue of ultimate fact in the present offense has been previously determined in favor of the defendant in a valid and final judgment.

   * Note: If the defense of double jeopardy or collateral estoppel can be established, the case is subject to dismissal.

2. Defenses related to the denial of the defendant’s right to a speedy trial.
   • • The defendant’s Sixth Amendment right to a speedy trial has been violated.
     • The applicable statutory or procedural speedy trial time limitations have not been complied with.

   * Note: If the defense of the denial of a speedy trial can be established, the case is subject to dismissal.

3. The defense of necessity.
   • • The defendant drove while intoxicated because it was necessary to do so in order to obtain treatment for an injury or illness or to save a life.

   * Note: This defense must be affirmatively raised and established by the defendant. If established, this defense may be used by the jury to acquit the defendant.

4. The defense of duress.
   • • The defendant drove while intoxicated in order to avoid death or serious injury.

   * Note: This defense must be affirmatively raised and established by the defendant. If established, this defense may be used by the jury to acquit the defendant.

5. The defense of entrapment.
   • • The police induced the defendant to commit the offense for the purpose of obtaining evidence and the defendant would not otherwise have committed the offense.

   * Note: This defense must be affirmatively raised and established by the defendant. If established, this defense may be used by the jury to acquit the defendant.

6. The defense of the margin of error rule.
   • • The BAC reported by the prosecution’s breath testing instrument, when adjusted by the instrument’s margin of error, does not exceed the legal limit.

   * Note: If this defense is recognized locally and can be established, the prosecution will be denied the use of the statutory presumption in a DUI or DWI case, and a “per se” offense will be subject to dismissal.

7. Defenses related to the enhancement of a drinking-driving offense.
   • • One or more of the alleged prior convictions did not occur within the statutory period of enhancement.
     • One or more of the alleged prior convictions is not a “conviction” under local law.
     • One or more of the alleged prior convictions is constitutionally invalid because the defendant entered an uncounseled guilty plea in the prior case and it cannot be established that the defendant was adequately advised of, and knowingly waived, his or her constitutional rights in the prior case.

   * Note: If any of these defenses can be established, the underlying drinking-driving offense cannot be enhanced by the prior conviction.

If you have been arrested for DUI, contact TeamDUI.com for a no cost case analysis with a highly-skilled DUI-DWI attorney in your area. We are available 24/7 at 1-844-TEAM-DUI (1-844-832-6384) or you may submit your case details for an attorney to contact you.