Common DWI/DUI Defenses

I recently received a NHTSA packet titled “Challenges and Defenses II: Claims and Responses to Common Challenges and Defenses in Driving While Impaired Cases”. I thought it would be useful to share this information to those who are or have a loved one who is facing driving while impaired charges.

One of the most startling type of DWI Cases are those where the intoxicant was a legally prescribed or over the counter drug. It is a commonly held misconception that these cases are defensible under the “entitlement doctrine”. When using the entitlement defense, the defendant’s lawyer argues that since his client was legally entitled to consume the substance he was intoxicated by at the time of his arrest, it is not the defendants fault and therefore he is not guilty.

Why It May Not Work: There is one fatal flaw to this defense, and that is that the crime of DUI does not require proof that the defendant intended to become intoxicated. Regardless of how the intoxication occurred, the defendant still made the decision to get in a vehicle and drive while intoxicated.


Another defense that commonly comes into play when legally prescribed or OTC drugs are involved is the “below the therapeutic dose” defense. During the trial the defendant’s lawyer argues that the defendant was not actually impaired at the time of arrest and tries to prove this by introducing evidence that the drug levels in the defendant’s blood were below therapeutic levels and therefore not capable of causing impairment.

Why It May Not Work: Some drugs can cause impairment even when they are present in below therapeutic levels and the prosecutor can pull in a drug recognition expert to attest to that. Furthermore, some drugs cause impairment just by their very nature. For example, Ambien is a powerful sleep aid that will cause impairment while driving even in small doses.


In many states, Ambien related DUI cases are very common. Those who are prescribed Ambien often experience unusual side effects, such as sleepwalking or vivid dreams. As a result of this, an “amnesia defense” has developed in these DUI cases. The defendant’s lawyer asserts that his client was unconscious or cannot remember what happened while the DUI occurred due to the side effects of Ambien and therefore is not legally responsible.

Why It May Not Work: The unusual side effects of Ambien increase when the subject has been drinking or taking a larger than recommended dose. The prosecutor in these cases can and will take a microscope to every detail of what happened the day of the arrest. If there is any improper usage at all, even a glass of wine at dinner, the defense will be invalidated. Another problem with this defense is that a person is not truly unconscious when experiencing these Ambien side effects. They may suffer from amnesia and be unable to recall the events that occurred but they are in fact conscious.


If you or a loved one has taken Ambien or other prescription drugs and has been charged with a DUI, you should call our office at 718-517-3007 immediately. We have the right skills and experience to handle your case.


- Kevin P. McKernan