Workplace Drug Testing Laws in Wisconsin: What Employers Can Do

Federal law does not comprehensively regulate private-sector drug testing. The Occupational Safety and Health Act (OSHA) and Americans with Disabilities Act (ADA) provide limited protections. Under the ADA, 42 U.S.C. § 12101 et seq., employers cannot use drug test results as automatic grounds for termination if an employee is in recovery from addiction (classified as a disability). The Drug-Free Workplace Act, 41 U.S.C. § 8102, requires federal contractors and certain grant recipients to maintain drug-free workplaces but does not mandate testing for private employers.

The Equal Employment Opportunity Commission (EEOC) enforces the ADA and ensures testing policies do not discriminate based on disability or protected characteristics. States retain primary authority over drug testing regulation in the private sector. The Department of Labor has limited involvement except in safety-sensitive positions (e.g., transportation, nuclear facilities). Federally, employees in transportation and certain safety-sensitive industries may be subject to mandatory testing under DOT regulations (49 C.F.R. Parts 40 and 382). However, most private-sector testing is governed by state law, making Wisconsin's comprehensive statute a significant protection for employees.

Wisconsin Statute § 111.31 provides one of the most comprehensive state-level drug testing frameworks in the United States, offering substantially stronger protections to employees than federal law alone. Wisconsin law applies to all employers with employees in the state, regardless of size—there is no employer threshold, making the law applicable even to small businesses.

Wisconsin permits drug testing only in limited circumstances: (1) as a condition of employment before hiring, (2) for employees in safety-sensitive positions with reasonable cause, (3) after a workplace accident causing injury, or (4) during the course of a routine fitness-for-duty examination. The statute explicitly prohibits random drug testing of current employees without individualized reasonable cause, which is a significant protection absent in federal law. Reasonable cause requires documented, articulable, objective facts based on specific employee conduct or behavior, not mere suspicion.

Unlike federal law, Wisconsin requires all testing to be conducted by certified laboratories accredited by the Substance Abuse and Mental Health Services Administration (SAMHSA). Wisconsin law mandates a confirmation test (typically GC-MS testing) for any positive preliminary result, at employer expense. Employers must follow strict chain-of-custody procedures. Results must be provided to the employee within five business days, and the employee may request a retest at their own expense within seven calendar days—the cost of the initial test cannot be passed to the employee.

Wisconsin provides unique remedies unavailable under federal law. An employee may bring a civil action under Wis. Stat. § 111.335 for violations, seeking damages up to $40,000 plus actual damages, costs, and reasonable attorney fees. This creates real financial accountability for employers. Additionally, Wisconsin law explicitly protects employees' off-duty conduct: a positive test result for marijuana or its metabolites alone does not justify termination, as Wisconsin decriminalized small amounts of marijuana for personal use. The law also provides protection for employees in drug rehabilitation programs—testing positive for substances related to lawful medical treatment cannot be the sole basis for adverse employment action.

Wisconsin law contains several important exceptions and limitations. First, the reasonable-cause requirement for current employees does not apply to certain safety-sensitive positions such as commercial drivers, security personnel, law enforcement, healthcare workers in direct patient care, and positions involving operation of heavy machinery. Even in these roles, the employer must still use certified laboratories and follow chain-of-custody procedures. The reasonable-cause exception also does not apply to drug testing conducted as part of a workplace accident investigation—if an employee is injured at work, the employer may test without prior individualized reasonable cause, though safety-sensitive position standards still apply.

Second, post-termination drug testing is not covered by Wis. Stat. § 111.31, meaning an employer cannot be held liable under the statute for testing conducted after employment has ended. Third, employees are not protected from positive test results for illegal drugs when those substances have legitimate medical purposes (e.g., prescription opioids, benzodiazepines prescribed by a physician). The statute protects lawful medical use, so a positive result for a prescribed medication cannot be the sole basis for termination, but the employer may still investigate actual impairment. Fourth, the law applies only to employees and not to independent contractors or volunteers, though an employer's misclassification of a worker as a contractor may itself violate Wisconsin labor law.

Fifth, marijuana metabolite testing presents a gray area. Although Wisconsin has not legalized recreational marijuana (as of 2025), it has decriminalized small amounts. Employers may still test for marijuana, but a positive result alone, without evidence of on-duty impairment or safety violation, may not be sufficient grounds for termination in safety-sensitive contexts—employers must document specific workplace impact. Sixth, employers are not required to offer rehabilitation or accommodations for substance use disorder; the ADA protects employees in recovery, but only those who have completed treatment or are actively enrolled in a treatment program. An employee currently using illegal substances is not protected from discharge.

Step 1 — Document Everything: If you believe your employer violated Wisconsin drug testing law, begin by gathering all documentation. Collect copies of any written notice of testing, the actual test results (request these in writing if you haven't received them), any chain-of-custody documentation, witness statements from colleagues who may have observed the testing process, dated notes about what happened before the test (did your employer specify reasonable cause?), medical records showing any prescribed medications you were taking, and records of any internal complaints you made to HR about the testing procedure. Keep originals safe and make backup copies.

Step 2 — Understand the Internal Complaint Process: Although not required by Wisconsin law, send a written complaint to your employer's HR department or management documenting the alleged violation. Use certified mail or email to create proof of delivery. Describe specifically which Wisconsin Statute § 111.31 requirement was violated (e.g., 'I was tested without reasonable cause,' 'results were not provided within five business days,' 'testing was not done by a certified laboratory'). Request a written response and preserve all communications. This creates an internal record and sometimes prompts employers to correct the violation or settle informally. Document any retaliation that occurs after your complaint.

Step 3 — File with the Appropriate Agency or Court: Wisconsin does not have a dedicated state agency (like the EEOC) that investigates drug testing violations. Instead, you must file a civil lawsuit directly in Wisconsin circuit court under Wis. Stat. § 111.335. You can file in the county where you work or where you live. The statute does not have a specific filing deadline embedded in the statute itself, but Wisconsin uses a three-year statute of limitations for personal injury actions (Wis. Stat. § 893.55), which applies to drug testing claims. You have three years from the date of the violation to file suit. You do not need to exhaust administrative remedies first—you may go directly to court. Contact a Wisconsin employment law attorney to file the civil complaint. Alternatively, if the drug testing violation also violates the ADA (e.g., you were tested and terminated because of a disability related to substance use disorder recovery), you may file with the EEOC at eeoc.gov or by calling 1-800-669-4000 and designating the Milwaukee EEOC office (414-805-1500).

Step 4 — Expect the Investigation and Court Process: If you file a civil lawsuit, the employer will be served with the complaint. The case enters the court system, where discovery occurs (both sides exchange documents and take depositions). The court may order the employer to produce lab results, testing records, and personnel files. This process typically takes 6 to 18 months before trial, though many cases settle during discovery once the employer realizes the violation will be costly to defend. The burden is on you to prove the employer violated Wis. Stat. § 111.31 by a preponderance of the evidence (more likely than not). The court may award you damages up to $40,000 (statutory cap) plus any actual damages you can prove (lost wages, emotional distress, medical bills), costs, and reasonable attorney fees. If the case involves ADA violations filed with the EEOC, the EEOC will investigate and issue a right-to-sue letter, allowing you to file in federal court within 90 days.

Step 5 — Consult an Attorney Early: Contact a Wisconsin employment law attorney specializing in drug testing or workers' rights as soon as you suspect a violation. Many offer free consultations. An attorney can evaluate whether your specific facts constitute a violation, calculate potential damages, and handle all filing and court procedures. Wisconsin employment lawyers typically work on a contingency basis for drug testing cases (they take a percentage of the settlement or judgment rather than an upfront fee), making representation affordable. Attorneys can also advise whether you have claims beyond the drug testing statute (e.g., intentional infliction of emotional distress, defamation if the employer disclosed your positive result). Given the $40,000 statutory cap, cases involving significant additional damages or publicity warrant prompt legal action.