The station breath test in Michigan: Intoxilyzer 9000 and DataMaster

The breath test given at the police station or jail after an OWI arrest is run on an evidential instrument managed by the Michigan State Police, and as of 2026 that instrument is the Intoxilyzer 9000.^[1] Before it, Michigan used the DataMaster DMT, which was at the center of a 2020 case in which a contractor's technicians were charged with falsifying service records.^[2] The State Police rules, rewritten in 2023, govern the instruments, the operators and how samples are taken.^[3] This page explains those rules. How results are challenged in court is on how breath test results are challenged.

Who runs the breath-test program

The Vehicle Code requires the Department of State Police to make uniform rules for administering chemical tests.^[11] MSP describes itself as "legislatively mandated" to manage the fleet of breath instruments installed in county jails and other locations, and says its Forensic Science Division regularly inspects the instruments, oversees the program and keeps the required records.^[1] A state fund administered by MSP may be used only to run the fund, buy and maintain breath-testing equipment, and train police to use it.^[12]

The Intoxilyzer 9000

MSP says Michigan uses the Intoxilyzer 9000, made by CMI Inc., and that MSP validated its performance independently in 2023 before adopting it.^[1] Officers must be certified to operate it through online and in-person training and a written exam, and must recertify every two years.^[5] MSP's website lets anyone look up the subject tests run on a given Intoxilyzer 9000 by entering its serial number, with personal information redacted.^[5]

The State Police pages cited here do not give the date each location switched from the DataMaster, or say whether the Intoxilyzer 9000 checks a known alcohol standard with every test. The second point decides which accuracy-check and inspection schedule below applies, so this page does not state it.^[1][13][14]

The rules for the instruments

The breath-alcohol rules (R 325.2651 to 325.2658) carry a 2023 amendment history entry, define "department" as the Department of State Police, and rescind R 325.2654 and R 325.2656.^[3] Their main requirements:

• Evidential and preliminary instruments must meet NHTSA's "Model Specifications for Devices to Measure Breath Alcohol," and operators may use only equipment the department approves.^[15]
• An instrument that does not test a known standard with each subject must be accuracy-checked at least weekly and read within plus or minus 5% using a controlled device; one that does test a standard with each subject needs no weekly test.^[13]
• Instruments that do not test a standard with each subject must be inspected and certified within 120 days of the last inspection; those that do must be inspected at least twice a year.^[14]
• If the instrument checks a known ethanol standard during a subject's test, the reading must be between 0.074 and 0.084 g/210 L.^[16]

Two cautions when reading older material. The DataMaster was Michigan's instrument in 2020, but it is not the instrument MSP names today.^[2][1] And the Traffic Benchbook, updated in August 2026, still quotes the PBT procedure as R 325.2655(2) with approval by "[LARA]," while the current rules put that procedure in R 325.2657a under State Police approval.^[4][17][3]

The operator

The rules define five operator classes; a Class III operator is certified to run a subject test on an evidential instrument, and a Class IVB operator to calibrate and repair one.^[18] A Class III operator must already hold Class II certification, complete an approved course, score at least 70% on a written exam, and show proficiency on an evidential instrument.^[19] Class III operators certified after January 1, 2022 must recertify every 2 years; those certified earlier had to recertify before December 31, 2023 and every 2 years after; a lapsed operator must retake the course but may testify about tests given while certified.^[6] MSP may suspend an operator's certification for not following its rules, policies and procedures.^[20]

How the test is given

1. The person is observed for at least 15 minutes by a certified operator before the sample, without smoking, regurgitating or putting anything in the mouth other than the mouthpiece.^[21] See the 15-minute observation rule.
2. The first sample is analyzed. Its result alone meets the evidentiary requirements.^[7]
3. The operator requests a second sample to confirm the first, unless something found in the mouth could interfere.^[7]
4. If the second result differs from the first by more than the allowed amount, a third sample is requested; if the third does not agree with either, the person is asked for a blood or urine sample.^[9]
5. Results are expressed in grams per 210 liters of breath, truncated to two decimals, or three if the instrument is set up to report three.^[16]

First result (2-decimal instrument)	Allowed difference for the second
0.00 to 0.14	Plus or minus 0.01.[8]
0.15 to 0.24	Plus or minus 0.02.[8]
0.25 to 0.34	Plus or minus 0.03.[8]
0.35 or more	Plus or minus 0.04.[8]

At 0.35 or more on any breath test, the operator must request medical assistance; failing to do so does not affect the result.^[22]

The 2020 DataMaster records case

As of May 2020 the DataMaster DMT was the evidentiary instrument used across Michigan, with 203 units in the state.^[2] MSP's contract with Intoximeters Inc. for maintenance, repairs and 120-day inspections began September 1, 2018, and the two technicians later charged serviced the Lower Peninsula instruments.^[2] Discrepancies came to light in a routine technical review by MSP's Breath Alcohol Program on January 2, 2020.^[2]

The records at issue involved the instruments at the Beverly Hills Police Department and the Alpena County Sheriff's Office. MSP temporarily removed all instruments from service, its own certified staff took over maintenance from January 10, 2020, and the contract was terminated effective April 9, 2020.^[2] One technician falsified three certifications for the Alpena County instrument, creating one on a spare DataMaster at his home and cutting and pasting the others.^[10] He pleaded guilty on October 28, 2020 to nine counts and was sentenced to 36 months' probation with the first nine months in jail; charges against the other technician were dismissed on December 9, 2020 for lack of venue and evidence.^[10]

The Attorney General's releases cited here do not report how the case affected individual OWI prosecutions.^[10]

How the result is treated in court

A breath result is admissible and is presumed to be the same as the person's level at the time of driving.^[23] Jurors are told they "may infer" that, may give the test the weight they think it deserves, and should consider whether the test was technically accurate, whether the equipment was properly maintained, whether the test was given correctly, and whether the person giving it was properly trained.^[24][25] On a written request to the prosecutor, test results must be provided at least 2 days before trial, or the prosecution may not use them.^[26] See the evidence in an OWI case and discovery and test records.