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Defenses to DUI in Michigan

Admission of Evidence of DUI in Michigan

Since probable cause is needed for a police officer to stop a vehicle, a defendant can challenge the sufficiency of that evidence. Police officers need only provide visual observations of impaired driving to satisfy probable cause, but if that is lacking, the defendant can exclude the evidence as an unreasonable search and seizure under the 4th Amendment.

Evidence from the field sobriety tests can be admitted to establish probable cause to arrest, but each can be excluded based on a number of challenges. The Nystagmus test can be challenged for incorrect administering of the test based on insufficient passes of the stimulus and insufficient time for each pass. Also, the test conditions can be challenged if the driver is made to face the patrol car lights. Similarly the walk and turn test and the one leg stand test can be excluded if the defendant can prove incorrect instructions or inadequate test conditions.

Results from any chemical tests are generally admitted, but the defendant can challenge them based on flaws in their reliability or on the timeliness of the administration of the test.

Finally, evidence of prior DUI convictions cannot be admitted against the defendant. Such evidence represents character evidence, since the evidence only proves that the defendant has done the act before and therefore must be of such a character to do it again. Character evidence is barred under MRE 401. If the evidence is admitted for another reason (such as to prove a scheme or plan), then the judge will give limiting instructions to the jury as to how they should treat the evidence.

Defenses to DUI in Michigan

There are a number of defenses against a DUI charge, which first begin with the defense that the police officer did not have sufficient probable cause to stop the vehicle. Absent a traffic violation, a defendant can argue that their driving was not visibly impaired. Additionally, a defendant can argue that there was insufficient probable cause that the defendant was driving while visibly impaired, which is necessary for a DUI arrest. The defendant can challenge any of the three field sobriety tests, which include the Horizontal Gaze Nystagmus Test, the Walk and Turn Test, and the One Leg Stand Test. The admissibility of the Horizontal Gaze Nystagmus Test can be challenged by not being correctly administered via lack of passes or lack of time for each pass, both of which are common. Also, having the driver face the patrol car can also be used to challenge the test since the patrol car lights can cause the involuntary twitching. The most common bases for challenging the Walk and Turn Test is when the officer fails to give the right instructions (including the correct number of steps), fails to provide appropriate test conditions, or fails to use the right scoring method (two out of eight is a failure). Lastly, the driver can challenge the One Leg Stand Test for incorrect instructions, incorrect time of elevation, or inadequate test conditions.

A defendant can also raise the defense of inadequate chemical testing via breath testing by arguing that testing mechanism does not function properly and thus does not produce accurate results. Also, urine testing can be challenged as not reliable since it is not a complete testing method. Another defense that can be raised is that any alcohol that was present in the defendant was consumed pursuant to a religious service, which must be protected under the free expression clause of the First Amendment.


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