Big Three Drug Testing — GM, Ford, Stellantis

Last verified: April 2026

Why the Big Three Matter

Detroit cannabis policy cannot be discussed without the Big Three automakers and their suppliers. The city’s economic gravity well — and its largest unionized workforce — runs through GM, Ford, and Stellantis, and through hundreds of Tier 1 and Tier 2 suppliers in the metro region. Federal contractor status, Department of Transportation safety rules, and union collective bargaining agreements all override state cannabis legality in the workplace.

The Drug-Testing Posture

General Motors — The Pilot Program

GM’s headquarters at the Renaissance Center anchored the downtown skyline since 1996, though in early 2025 GM announced plans to move its HQ to the new Hudson’s Detroit tower on Woodward Avenue. GM has long maintained one of the auto industry’s strictest pre-employment drug-screening programs, including hair-follicle testing that can detect cannabis use weeks back.

Under pressure from a 2021–2022 hiring shortage, GM piloted the removal of pre-employment marijuana screening at certain assembly plants, including Flint Assembly and Fort Wayne (Indiana). GM spokeswoman Kim Carpenter told media the company was “currently conducting some pilots to determine which specific substances we test for during these screenings.” UAW Local 598 Shop Chairman Eric Welter told the Detroit Free Press that mandatory cannabis testing was deterring qualified applicants.

As a federal contractor (Department of Defense, GSA fleet sales), GM remains subject to the Drug-Free Workplace Act for affected employees regardless of the pilot program.

Ford Motor Company — Continued Screening

Ford’s world headquarters in Dearborn (Wayne County, immediately west of Detroit) and its Michigan Assembly, Rouge, and Michigan Central campuses make Ford the metro area’s largest single private employer. Ford continues pre-employment drug screening that includes THC for many positions; safety-sensitive roles (mechanical, manufacturing, fleet drivers) are tested under stricter post-incident and random regimes.

Stellantis — Continued Screening

The Jeep, Ram, Chrysler, and Dodge parent (formed by the 2021 PSA-FCA merger) is headquartered in Auburn Hills, Oakland County. Stellantis still conducts a urine-based pre-employment drug screen that includes marijuana, though the company has shortened its dexterity testing and added in-person hiring events at Detroit’s Conner Center to compete for assembly labor.

UAW Workforce

The United Auto Workers master agreement with each of the Big Three sets out drug-testing protocols for represented members. Most CBAs allow for-cause and post-accident testing and mandate confirmation testing, but typically prohibit suspicionless random testing for non-safety-sensitive roles. An arbitrator’s decision in ZF Active and Passive Safety and UAW Local 1181 (March 2020) upheld a 10-day suspension for an employee whose marijuana odor and positive drug test together established just cause under the CBA — illustrating that even with MRTMA, cannabis use detected on-shift remains discipline-eligible.

Tier 1 / Tier 2 Suppliers

Magna, Lear, BorgWarner, Adient, Aisin, ZF, and dozens of other suppliers operate Detroit-area plants under prime-contractor flow-down clauses that often mandate Drug-Free Workplace Act compliance. Federal contractor status under Executive Order 12564 and the Drug-Free Workplace Act of 1988 requires zero-tolerance drug policies for affected employees, regardless of state-law cannabis legalization. The flow-down obligation propagates federal compliance requirements through the entire automotive supply chain.

DOT / FMCSA — Trucking and Logistics

Commercial driver’s license (CDL) holders are governed by Federal Motor Carrier Safety Administration Part 382 drug-testing rules, which include pre-employment, post-accident, random, return-to-duty, and reasonable-suspicion testing. A failed drug test triggers SAP (Substance Abuse Professional) evaluation and CDL clearinghouse reporting under the Drug & Alcohol Clearinghouse that came online in January 2020. Detroit’s logistics workforce — the Ambassador Bridge alone recorded 1.9 million commercial truck crossings in 2025, and freight is the metro’s largest logistics segment — operates entirely under FMCSA’s zero-tolerance regime.

Michigan Medical Patient Employment Protections — Limited

Two cases define Michigan’s narrow employment protections for medical cannabis patients:

• Casias v. Wal-Mart Stores, Inc., 695 F.3d 428 (6th Cir. 2012) — The Sixth Circuit affirmed dismissal of Joseph Casias’s wrongful-discharge claim. Casias, a Michigan medical patient with sinus cancer and an inoperable brain tumor, was fired by the Battle Creek Walmart after a post-injury drug test came back positive. The court held that the Michigan Medical Marihuana Act “does not regulate private employment” and confers no employment protections.
• Eplee v. City of Lansing, 327 Mich. App. 635 (2019) — The Michigan Court of Appeals held the MMMA’s Section 4(a) “does not provide an independent right protecting the medical use of marijuana in all circumstances, nor does it create a protected class for users of medical marijuana.” Angela Eplee’s conditional employment offer at the Lansing Board of Water and Light was lawfully rescinded after a positive THC test.

The narrower Braska v. Challenge Manufacturing (2014) line of cases preserves medical patients’ eligibility for unemployment benefits if they had a pre-existing entitlement that was denied based on medical use — but that protection does not extend to the underlying employment decision itself.

The Practical Map for Detroit Cannabis Consumers

Practical Advice for Detroit Cannabis Consumers

• If you work for or are interviewing with a federal contractor (any Big Three or many Tier 1/Tier 2 suppliers for DoD or GSA work), do not consume cannabis
• If you hold or are pursuing a CDL, do not consume cannabis
• For UAW-represented positions, understand the CBA’s testing protocol; for-cause and post-accident testing remains routine
• For metro-Detroit healthcare roles, expect THC pre-employment screening
• State legalization does not protect federally-tested employees

Related on this site: Detroit Federal Employment Map, TACOM, Veterans & VHA Directive 1315.