What 2025 Act 99 actually did
Act 99 added the words “or oral fluids, or both” to Wis. Stat. §343.303, the preliminary breath test statute. That is the entirety of the structural change. It did not amend §343.305 (implied consent), it did not amend §346.63 (the OWI statute itself), and it did not create a new evidentiary chemical test. The saliva swab is now a tool an officer can use during a traffic stop, on the same legal footing as the existing roadside breath PBT for alcohol.
Why that matters: the §343.303 PBT rule has always treated screening results as probable-cause evidence only. The screening result is admissible to show the officer had reason to arrest, that a chemical test was properly requested, or to rebut a probable-cause challenge. It is not admissible to prove impairment or guilt at trial. Act 99 carried that rule forward.
The single most-misreported point: headlines have framed the saliva test as “mandatory” or compared it to the breathalyzer. It is neither. It is a preliminary screen. Refusing the swab itself does not trigger automatic license revocation. Refusing the post-arrest blood draw under §343.305 does. The two are different tests at different stages of the stop.
Presence, not impairment
The Abbott SoToxa and similar oral-fluid devices detect the presence of a substance in saliva at the time of the swab. They do not measure quantity (the device returns a binary positive or negative on each panel) and they do not measure impairment. This is especially significant for cannabis. Delta-9 THC can produce a positive oral-fluid result for hours after the impairing effect has fully worn off, and recent cannabis use in a state where it is legal (Illinois since 2020, Michigan since 2018, Minnesota retail since September 16, 2025) can surface on a Wisconsin roadside test long after the driver has any measurable effect.
A positive saliva screen tells the officer two things: (1) probable cause for the OWI arrest, and (2) probable cause to request a blood draw under §343.305. The blood draw is the test that actually decides the criminal case under §346.63(1)(am), Wisconsin's zero-tolerance prohibited-substance OWI statute, which makes any detectable delta-9 THC, cocaine, or other listed substance in blood a per se OWI without proof of impairment.
The substance panel
Public framing of the law has settled on three categories: THC, opioids, and stimulants. The stimulant class is broad and includes amphetamines, methamphetamine, and cocaine. The actual substances detected on any given stop depend on the device the agency uses. The Abbott SoToxa, the most common roadside instrument in Midwestern jurisdictions, runs a six-substance panel:
- THC (delta-9 tetrahydrocannabinol)
- Amphetamine
- Methamphetamine
- Cocaine
- Opiates (heroin and prescription opioid metabolites)
- Benzodiazepines
Local agencies will deploy on different schedules. As of May 2026, several departments around the state are still working through training and procedure adoption before they begin using the device on actual stops. If you were tested in the very early weeks of the program, the training and procedural records of the testing officer are cross-examinable at suppression.
Refusal: what changes, what doesn't
| Test | Statute | Refusal triggers automatic revocation? |
|---|---|---|
| Roadside saliva swab | §343.303 (preliminary screening) | No |
| Roadside breath PBT | §343.303 (preliminary screening) | No |
| Field sobriety tests | Voluntary, no statute | No |
| Post-arrest evidentiary blood draw | §343.305 (implied consent) | Yes, 12 months for first refusal |
| Post-arrest evidentiary breath test | §343.305 (implied consent) | Yes, 12 months for first refusal |
The refusal-hearing process applies only to the §343.305 evidentiary test. See our refusal hearing spoke for the 10-day deadline and the three-element hearing scope.
Defense angles after Act 99
The law is two months old and there is no Wisconsin appellate case law interpreting it. Several defense angles are essentially open territory for the next 12 to 24 months:
Reasonable suspicion to request the swab
Like the breath PBT, the oral-fluid screen requires reasonable suspicion of impaired driving. The officer cannot demand the swab on the basis of a speeding stop alone. Indicators of drug use specifically (not just alcohol) are required. The reasonable-suspicion record is built on the squad video and the police report, both of which are routinely reviewed in suppression motions.
Device reliability and training
Each device has manufacturer-specified training requirements, calibration schedules, and procedural protocols. In the early months of statewide deployment, training records and calibration logs are uneven. Where the record is incomplete or the operating officer was not certified on the device, the screen result and the probable cause it produced are challengeable.
Chain of custody on the swab
Oral fluid devices return a result on disposable cartridges that may or may not be preserved depending on agency policy. If the cartridge is discarded after the result is recorded, the defense cannot independently test it. That is itself an evidentiary issue, particularly in a case that turns on whether the screen was actually positive or whether the officer mis-read it.
Lookback window for cannabis specifically
Oral-fluid THC detection windows are not the same as impairment windows. Recent peer-reviewed studies put oral-fluid delta-9 THC detection at roughly 8 to 24 hours after use, well past the typical 3 to 4 hour impairment window. A driver who used legally in Illinois on Friday and is stopped in Pleasant Prairie on Saturday morning may register positive without being remotely impaired. The state still has to prove zero-tolerance prohibited-substance OWI from the blood draw, not the saliva screen, but the saliva screen is what justifies the arrest in the first place.
What this means for cross-border traffic
Wisconsin is now bordered on three sides by states with active adult-use cannabis markets: Illinois (recreational since 2020), Michigan (recreational since 2018), and Minnesota (retail sales started September 16, 2025). A Wisconsin resident who buys legally in any of those states is in possession of a Schedule I controlled substance under Wisconsin law the moment they cross the border. With Act 99 now in effect, the same conduct also creates exposure to a roadside saliva test for any THC still detectable in oral fluid, which can be days after the last use.
I-94 enforcement south of Racine and I-43 / I-94 enforcement near the Kenosha-Illinois state line have been the most reliable corridors for these stops historically. With oral-fluid screening now available, expect the volume of drug-OWI charges from those corridors to rise.
If you've already been swabbed
Whether you submitted to the swab, refused it, or were never offered it, the case turns on the §343.305 blood draw and the totality of the stop. The first 24 hours after the arrest are the highest-leverage window for preserving evidence: the squad video, the device calibration record, the training records of the operating officer, the chain of custody on both the swab and the blood draw. We file preservation requests the same day a case comes in.
Free, confidential consultation: Call or text (262) 632-5000. We have defended Wisconsin OWI and drug cases continuously since 1994 and we are already taking saliva-test cases under Act 99.
