Wisconsin Act 99: New Law Authorizes Oral Fluid Testing in OWI Investigations

Analysis of 2025 Wisconsin Act 99 (Senate Bill 678)

Wisconsin has enacted a significant update to its implied consent and intoxicated operation laws. 2025 Wisconsin Act 99, signed into law in March 2026, authorizes law enforcement officers to use oral fluid screening as a preliminary tool when investigating suspected intoxicated operation of vehicles.

The legislation expands the scope of preliminary testing beyond traditional breath samples, allowing officers to request a sample of a person’s oral fluids to detect the presence of controlled substances or alcohol. This change applies not only to motor vehicles on the road but also to the operation of ATVs, UTVs, off-highway motorcycles, boats, and snowmobiles.

For individuals facing OWI investigations, this law introduces a new method of roadside evidence collection. If you have been subjected to an oral fluid test or are facing charges related to intoxicated operation, it is essential to consult with an experienced Wisconsin OWI defense attorney to understand how this new evidence may be used in your case.

What Is Oral Fluid Screening?

Oral fluid screening typically involves using a swab to collect a saliva sample from a person’s mouth. Under Act 99, this test serves as a “preliminary screening,” similar to a Preliminary Breath Test (PBT).

Prior to this law, roadside preliminary screenings in Wisconsin primarily focused on breath samples to detect alcohol. The inclusion of oral fluids provides law enforcement with a statutory mechanism to screen for drugs and other controlled substances more efficiently during a roadside stop.

Scope of the New Law

Act 99 amends several chapters of the Wisconsin Statutes to ensure that the oral fluid testing standard is uniform across different types of vehicle operation. The requirement to provide a sample applies when an officer has probable cause to believe a person is violating intoxicated operation laws for:

• Motor Vehicles: Standard OWI investigations under Wis. Stat. § 343.303.
• All-Terrain & Utility Terrain Vehicles (ATVs/UTVs): Under Wis. Stat. § 23.33.
• Off-Highway Motorcycles: Under Wis. Stat. § 23.335.
• Boats: Under Wis. Stat. § 30.682.
• Snowmobiles: Under Wis. Stat. § 350.102.

Use and Admissibility of Oral Fluid Results

The legal standards for oral fluid tests mirror those already in place for preliminary breath tests. Key provisions regarding the results include:

• Purpose of the Test: An officer may use the results solely to decide whether to make an arrest or whether to request a more formal chemical test (such as a blood draw).
• Limited Admissibility: The result of a preliminary oral fluid screening is generally not admissible in court. It can only be used in a legal proceeding to show that the officer had probable cause for an arrest or that a secondary chemical test was properly requested.
• Secondary Testing: A preliminary oral fluid test does not replace the formal chemical tests (blood, breath, or urine) authorized under Wisconsin’s implied consent law.

Privacy Protections and Sample Retention

Act 99 includes specific language regarding how oral fluid samples must be handled to protect the privacy of the individual:

• Limited Collection: Officers may only collect and retain a sample to the extent necessary to perform the preliminary screening.
• Mandatory Destruction: The law explicitly requires that the officer destroy the sample or return it to the person immediately after the test is conducted.
• Prohibition of Other Uses: Law enforcement is strictly prohibited from using or retaining the oral fluid sample for any purpose other than the preliminary screening.

Practical Impact on OWI Defense

The introduction of oral fluid testing may lead to an increase in arrests for Operating While Under the Influence of a Restricted Controlled Substance (RCS). Because these tests are now statutorily recognized, drivers should expect officers to request saliva samples more frequently if drug impairment is suspected.

However, like PBTs, these roadside devices are not infallible. Issues regarding the reliability of the device, the administration of the test, and the existence of actual probable cause remain critical areas for legal challenge.

Key Takeaways from Wisconsin Act 99

• New Testing Method: Law enforcement can now request oral fluid samples for preliminary screenings in intoxicated operation cases.
• Broad Application: The law covers motor vehicles, boats, snowmobiles, ATVs, and off-highway motorcycles.
• Probable Cause Tool: Results are primarily used to justify an arrest or a follow-up blood test and are generally not admissible as evidence of guilt at trial.
• Strict Retention Rules: Samples must be destroyed or returned immediately after the screening; they cannot be kept for DNA or other purposes.

What This Law Means Going Forward

Act 99 represents a move by the Wisconsin legislature to modernize roadside investigations in response to the increasing prevalence of drug-involved driving. While it gives law enforcement a new tool, it also establishes clear boundaries on how that tool can be used and how the resulting data must be destroyed. As these devices are deployed across the state, Wisconsin courts will likely be called upon to determine the specific technical standards for “approved” oral fluid devices.