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Understanding a DUI Arrest and Investigation in Michigan


Facing DUI charges? It’s important you understand how a DUI arrest and investigation in Michigan works.

The moment a police officer suspects a driver recently drank alcohol, they’ll begin a standardized DUI investigation before initiating a DUI arrest.

This very specific investigation is taught to police officers all over the country.

It’s very similar everywhere, but that doesn’t mean it will be performed correctly.

Are you facing DUI charges? Unhappy with your current attorney? Request a free consultation now.

dui arrest and investigation michigan

Often times, the officer receives the training only once for DUI arrest and investigation, and their test scores for administering these tests may be subpar at best.

DUI Investigation training was created by the National Highway and Traffic Safety Association (NHTSA) and is generally taught to all new officers in their training academy.

I Passed the Field Sobriety Tests. Why Did I Take a Breath Test on the Road?

The investigation includes the administration of field sobriety tests and preliminary breath tests (PBT).

It doesn’t matter if someone passes all the sobriety tests beforehand.

The PBT is still always administered, if possible.

It’s one of the strongest pieces of data used to make an arrest decision.

It’s important to understand all phases of the DUI investigation, which are described in detail below.

Phase One: Vehicle in Motion

The officer is trained to be watching the suspect’s driving before he pulls you over.

They’re looking for anything that is typically associated with impaired driving.

There’s a list of about 35 things associated with impaired driving, such as:

  • swerving,
  • rapidly changing speeds,
  • almost striking objects,
  • failure to use turn signals, etc.

Phase Two: Personal Contact

This phase includes their observations when approaching and interviewing the driver.

During this phase, they’ll decide whether to ask the driver to exit the vehicle for additional testing.

They’ll begin with questions about how much, what, where and when the suspect drank alcohol.

They may also ask where the driver came from, and where they were going to see if the answers make sense.

They’ll also be very observant when the have first contact with the driver looking at the condition of their clothing, eyes and particular odors like intoxicants.

The first two cognitive tests are the alphabet test (I’ve never seen them ask a suspect to recite the alphabet backwards) and the number counting test (which is always backwards).

The officer is looking for a variety of things including speech and accuracy/visual observations, like swaying.

Those are both non-standardized tests in a DUI investigation, meaning there isn’t a standard manner of administration and evaluation, unlike the three tests that follow.

The officer may also ask for two things simultaneously, as they’re trained that possible signs of impairment are displayed in response to this dual request.

For instance, the driver may forget to produce both documents, produce documents other than the ones requested, fails to see or overlooks one document while searching for the other, fumbles or drops their wallet or purse.

Additionally, they may ask distracting or interruptive questions during this process.

For instance, while retrieving the license the officer may ask, “without looking at your watch, what time is it?” and observe whether the driver ignores the question, answers the question but then forgets to resume obtaining their requesting documents, or supplies grossly incorrect information.

The officer will be very observant in the manner the driver exits the vehicle when requested.

Impaired drivers may do the following: have difficulty opening the door, uses the door for leverage, and keeps hands on the vehicle for balance.

Are you facing DUI charges? Unhappy with your current attorney? Request a free consultation now.

Phase Three: Field Sobriety Tests and Breath Test

There are three psychophysical tests called standardized field sobriety tests, which are to be administered and evaluated in a very specific standardized manner.

Significant deviation from the standardized administration and evaluation can invalidate the test.

Horizontal Gaze Nystagmus Test

The first standardized test is an eye examination called the Horizontal Gaze Nystagmus (HGN). Using a pen or finger held 12-inches from your head at eye level, they’ll move it back and forth looking for nystagmus which is “eye jerking.” When a person drinks alcohol, it keeps their eyes from moving smoothly.

When performing this test correctly and in the standardized manner, it’s noticeable and indicative of alcohol intoxication which will subsequently result in a DUI arrest.

The officer is looking for six clues total, three in each eye.

Four or more clues observed is a fail.

Walk and Turn

The second test is the walk-and-turn, where the subject starts with their right foot heel touching the toe of the left.

This is the instructional stance, during which the test is described and demonstrated.

When instructed, the subject will take nine heel-to-toe steps forward on an imaginary straight line, turn with small steps of their right foot then return nine heel-to-toe steps, all counting out loud and keeping their arms by their sides the entire time.

The officer is looking for several clues, such as:

  • Starting without being instructed,
  • walking off the line,
  • wrong number of steps,
  • not turning as instructed,
  • not walking heel to toe, and
  • lifting arms from their sides more than six inches.

Therefore, two or more observed clue failures will typically result in a DUI arrest.

One Leg Stand

The third test is a one leg stand. The subject is instructed to lift one leg approximately six inches off the ground and count to thirty.

The officer is looking for clues including starting before being instructed to do so, putting the foot down and raising arms for balance.

Therefore, two or more observed clue failures will typically result in a DUI arrest.

Preliminary Breath Test on Road vs Datamaster Breath Test in Police Station

Possibly the most commonly confused thing is the difference and purpose of the breath test offered in the road, in comparison to the breath test offered in the police station.

The breath test offered in the road, or on the scene of the investigation, is called a preliminary breath test (PBT).

The technology used in estimating a person’s breath alcohol content isn’t as sophisticated or accurate as the one in the police station.

It’s subject to more error.

It’s not specific to the alcohol contained in beverage drinks (ethyl alcohol), meaning it will test positive for other types of alcohol as well.

For that reason, it’s only used to make an arrest decision and not for purposes in determining guilt or innocence.

The penalty for refusing to submit to a PBT is only a fine with no license sanction, as long as the vehicle in operation wasn’t a commercial vehicle.

The breath test in the police station is called the Datamaster DMT.

It uses infrared light spectroscopy, which identifies ethanol molecules by a particular chemical bond using light absorption detection.

It’s specific to ethyl alcohol and is much more scientifically reliable for determining bodily alcohol content.

It’s the only chemical instrument used in Michigan for breath alcohol analysis for evidentiary purposes.

That means that the Datamaster results are the only results that can be used in court to prove guilt.

Refusal to submit to a Datamaster test can result in a six (6) month license suspension, and will generally be followed by the issuance of a search warrant to obtain a blood sample.

But here’s perhaps the most important takeaway.

You need a lawyer with significant scientific training.

Every DUI will involve a chemical test.

If your attorney lacks scientific expertise specific to DUI cases, they’re useless to you.

You may as well handle your case on your own.

Find an attorney with scientific expertise in DUI matters and a proven track record, including in a DUI investigation and trials.

Can a DUI Arrest Happen If I Did Not Take The PBT?

A police officer can only proceed with a DUI arrest if, based upon everything they observed, the evidence is supported by probable cause that the driver is likely driving while intoxicated.

Probable cause means evidence that would make a reasonably prudent person believe that a crime had been committed.

If the driver’s PBT results exceed .08 BAC, probable cause exists, even if the other tests were passed.

The reason is that a person can have no psychomotor impairment and still have an unlawful BAC.

If the PBT is refused, the officer must evaluate the rest of the evidence to determine if probable cause exists.

If a suspected driver passed the sobriety tests, then an arrest shouldn’t occur.

Can Standardized Tests Be Challenged In Court?

If the arrest decision was made primarily upon the results of the field sobriety tests and without a PBT result that equaled or exceeded .08 BAC, the suspected driver should consider challenging the sufficiency of probably cause for the arrest in court.

Many officers don’t administer the standard field sobriety tests correctly.

If they don’t, the arrest is subject to challenge which could cause the case to be dismissed.

Can The PBT Be Challenged In Court?

There are rules for the administration of the PBT as well, such as it cannot be administered without a 15 minute waiting period, during which nothing shall be placed inside the subject’s mouth.

Additionally the officer must have been properly trained and certified to operate the PBT.

Should the requirements not be met, the PBT results can be excluded from the probable cause DUI arrest claim.

Are you facing DUI charges? Unhappy with your current attorney? Request a free consultation now.

Barton Morris
Barton Morris has been providing high-quality legal representation in the area of state and federal criminal defense for more than 20 years.
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Barton Morris
Barton Morris has been providing high-quality legal representation in the area of state and federal criminal defense for more than 20 years.
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