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Chemical Testing and Ignition Interlock Devices in Michigan

Chemical Testing for DUI in Michigan

Chemical testing for a possible DUI offense in Michigan can be conducted via portable breath testing, evidentiary breath testing, blood testing, or urine testing. Under Michigan’s implied consent law, a driver is considered to have given consent once the police officer has reasonable cause to believe that the driver has committed a DUI offense, which would most likely result from failure of the field sobriety tests. Thus, a major issue with chemical testing would be if a police officer did not have sufficient probable cause for a DUI arrest, since there would not be any implied consent to validate the chemical testing. For blood testing, which requires a warrant, there can be issues with the sufficiency of the information that is used as the basis of the warrant.

Once consent has been established for chemical testing, police officers owe no duty to inform the driver which test they will use.  Additionally, the physician-patient privilege does not extend to the chemical tests conducted since the tests are generally done at the request of the police as opposed to testing that is requested by a physician for treatment purposes.

Note that one issue with chemical testing for narcotics is that it does not test for all drugs available and can be challenged since urine tests are not as reliable.

Ignition Interlock Devices in Michigan

Ignition interlock devices are implemented in Michigan for certain DUI offenses as well as for repeated DUI offenses. A breath alcohol ignition interlock device is a breath alcohol analyzer that is installed into the vehicle’s ignition and other control systems. The breath alcohol ignition interlock device measures the driver’s BAC level and does not allow the driver to operate the vehicle unless their BAC level is below 0.025. The devices are imposed if the driver is convicted of operating while intoxicated, operating in the presence of drugs, operating with an enhanced BAC, having two or more convictions within seven years, or having three or more convictions within ten years. Implementation often follows a period of revocation or denial of a DUI offender’s driving license, or can also be imposed as one of the conditions for a restrictive license.

If the ignition interlock device has multiple test failures during the monitoring period or if it detects tampering, the vehicle should be brought immediately to a service center to avoid the vehicle entering “lock-out” mode. Test failures, tampering, and other ignition interlock device violations (such as committing another DUI offense) can result in extending the period in which the ignition interlock device is required.


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