What 2025 Act 99 actually did
Act 99 made three changes to Wis. Stat. §343.303, and the third one is the one nobody mentions.
- It added “or oral fluids, or both” to the sample an officer may request.
- It struck the word “breath” throughout, so the section is now titled “Preliminary screening test” rather than preliminary breath test. Any material still calling this the PBT statute is using a superseded name.
- It imposed a destruction duty on the sample: “A law enforcement officer may collect and retain a sample of a person’s oral fluids only to the extent necessary to perform a preliminary screening test under this section and shall destroy the sample, or return the sample to the person, after conducting the preliminary screening test. A law enforcement officer may not collect or retain a sample of a person’s oral fluids under this section for any purpose other than a preliminary screening test.”
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. One asymmetry worth knowing: the motor-vehicle statute says an officer “may request” the sample, while the parallel recreational-vehicle provisions Act 99 also amended (§23.33(4g) for ATVs, §23.335(12)(e), §30.682 for boating, §350.102 for snowmobiles) say a person “shall provide” it. The rule on the road is not the rule on the water.
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
Oral-fluid screening 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, where the roadside screen and the statutory element are measuring different things: the screen reports presence in oral fluid, while §340.01(50m)(e) requires delta-9-THC in the blood at one or more nanograms per millilitre, excluding precursors and metabolites.
A positive saliva screen feeds two decisions: whether to arrest, and whether to request a chemical test under §343.305. The blood draw is the test that actually decides the criminal case under §346.63(1)(am), which prohibits driving with “a detectable amount of a restricted controlled substance” in the blood. Read §340.01(50m) before assuming that means zero tolerance across the board: cocaine and its metabolites, and methamphetamine, are any-amount substances, but delta-9-THC counts only at one or more nanograms per millilitre and only excluding its precursors and metabolites. Section 346.63(1)(d) additionally provides a prescription defence for methamphetamine, GHB, and delta-9-THC.
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, which § 343.303 requires be "approved by the department for this purpose." A commonly discussed instrument runs a six-substance panel:
- THC (delta-9 tetrahydrocannabinol)
- Amphetamine
- Methamphetamine
- Cocaine
- Opiates (heroin and prescription opioid metabolites)
- Benzodiazepines
Local agencies deploy on different schedules, and §343.303 only permits screening “using a device approved by the department for this purpose,” so which instrument an agency actually fielded, and when, is a question of fact. If you were tested in the early months after the March 15, 2026 effective date, the device-approval record and 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 took effect on March 15, 2026 and there is still no Wisconsin appellate case law interpreting it. Several defence angles are open territory:
The officer needs more than reasonable suspicion to ask
This is the most common misstatement about the new law, and it understates the defence. Section 343.303 requires that the officer have “probable cause to believe” the person is violating or has violated one of the listed OWI provisions, or, for commercial drivers, that the officer “detects any presence” of alcohol or a drug. In County of Jefferson v. Renz, 231 Wis. 2d 293 (1999), the Wisconsin Supreme Court held that this phrase means “a quantum of proof that is greater than the reasonable suspicion necessary to justify an investigative stop … but less than the level of proof required to establish probable cause for arrest.” So an officer who had just enough to stop the car does not automatically have enough to request the swab. That gap is the suppression target, and it is built on the squad video and the police report.
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.
The sample is destroyed by law, and that cuts both ways
Act 99 did not leave sample retention to agency policy. Section 343.303 now requires that the officer “shall destroy the sample, or return the sample to the person, after conducting the preliminary screening test,” and bars collecting or retaining oral fluid “for any purpose other than a preliminary screening test.” The practical consequences:
- The defence will never get to retest the sample. The only record of the result is the device output and the officer’s account of it, which makes the squad video and the device log central.
- Retention or downstream use of the sample is itself a statutory violation. If an agency banked oral fluid, sent it to a lab, or used it for anything beyond the roadside screen, that is a live issue.
Detection is not impairment, and for THC it is not even the element
We do not publish a detection-window figure here, because we have not located one attributable to an official government source. What the statutes give us is stronger anyway. The saliva screen shows presence at the roadside. The element the state must prove for a cannabis prohibited-substance OWI is set by §340.01(50m)(e): delta-9-THC “excluding its precursors or metabolites, at a concentration of one or more nanograms per milliliter of a person’s blood.” That is a threshold, not a zero-tolerance rule, and metabolites do not satisfy it. A driver who used cannabis lawfully in a neighbouring state days earlier can screen positive at the roadside and still fall below the statutory blood threshold. The screen justifies the arrest; the blood result decides the case.
What this means for cross-border traffic
Wisconsin borders states with adult-use cannabis markets while Wisconsin itself does not have one. A Wisconsin resident who buys lawfully across a state line is in possession of a controlled substance under Wisconsin law the moment they cross back. With Act 99 in effect, the same conduct also creates exposure to a roadside oral-fluid screen. What that screen cannot do is establish the §346.63(1)(am) element, which requires a blood concentration of one or more nanograms per millilitre of delta-9-THC under §340.01(50m)(e).
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.
