Guidance ≠ Rule: The Wisconsin Supreme Court Clarifies that DNR May Enforce the Spills Law Without Substance-Specific Rulemaking

1. Introduction

In Wisconsin Manufacturers and Commerce, Inc. v. Wisconsin Department of Natural Resources, 2025 WI 26, the Wisconsin Supreme Court confronted a high-stakes dispute about environmental enforcement and administrative law. The industrial trade association Wisconsin Manufacturers and Commerce (WMC) and Leather Rich, Inc. (a dry-cleaning business) sought to curtail the Department of Natural Resources’ (DNR) efforts to regulate per- and polyfluoroalkyl substances (PFAS) under Wisconsin’s “Spills Law” (Wis. Stat. § 292.01 et seq.). The respondents argued that the agency could not treat PFAS—or any “emerging contaminant”—as a “hazardous substance” unless it first completed formal rulemaking identifying each compound, its quantity, and concentration thresholds. The DNR countered that the plain text of the Spills Law already imbues it with broad authority to respond to any hazardous discharge in real time, and that its website statements and letters about PFAS were merely non-binding guidance.

The Supreme Court, reversing the court of appeals, sided with the DNR on every issue. The decision cements a new precedent: agency communications that merely explain how an unambiguous statute will be applied constitute “guidance documents,” not “rules,” and therefore need not go through Wisconsin’s formal rule-promulgation process. The ruling also confirms that § 227.10(2m)’s “explicit authority” requirement is satisfied where the legislature has granted an agency “broad but explicit” statutory power.

2. Summary of the Judgment

No Mandatory Rulemaking for Each Hazardous Substance. The Spills Law’s definition of “hazardous substance” (§ 292.01(5)) is “broad but explicit.” It does not compel DNR to list every substance, quantity, or concentration by rule.
Website Statements and Letters Are Guidance, Not Rules. Under § 227.01(13) a “rule” must have the force of law. DNR’s PFAS communications lacked coercive effect and therefore were “guidance documents” under § 227.01(3m).
§ 227.10(1) Not Triggered. Because guidance documents do not “govern” enforcement, the agency had no duty to promulgate its PFAS interpretation as a rule.
§ 227.10(2m) Satisfied. The Spills Law itself supplies “explicit authority” for DNR to apply reporting thresholds for hazardous discharges, including PFAS.
Outcome. The circuit and appellate decisions favoring WMC/Leather Rich were reversed; the case is remanded with instructions to enter judgment for the DNR.

3. Analysis

a. Precedents Cited and Their Influence

State v. Mauthe, 123 Wis. 2d 288 (1985) & State v. Chrysler Outboard, 219 Wis. 2d 130 (1998)
Demonstrated that courts have long enforced the Spills Law against specific contaminants without any substance-listing rules.
Citizens for Sensible Zoning v. DNR, 90 Wis. 2d 804 (1979)
Originated the five-part test for determining whether an agency statement is a “rule.” The majority applied that test, emphasizing the “effect-of-law” prong.
Service Employees International Union v. Vos, 2020 WI 67 (“SEIU”)
Distinguished “guidance documents” from “rules” and underscored that the former have no legal force. The court relied heavily on SEIU to classify DNR’s PFAS statements as non-binding.
Schoolway Transportation Co. v. DMV, 72 Wis. 2d 223 (1976) & Lamar Central Outdoor LLC v. DHA, 2019 WI 109 (2019)
Explained when an agency must promulgate a rule after changing its interpretation. The majority extended these cases, holding that applying an unambiguous statute to new facts requires no rulemaking.
Clean Wisconsin, Inc. v. DNR (I & II), 2021 WI 71 & 2021 WI 72
Introduced the “broad but explicit authority” concept under § 227.10(2m). The majority imported that rationale to uphold DNR’s ability to impose reporting thresholds.

b. Legal Reasoning

Statutory Interpretation of § 292.01(5).
The definition is intentionally open-ended (“any substance … which may pose a substantial hazard …”). Nothing in the text conditions DNR enforcement on prior rulemaking. The court treated this breadth as express legislative authorization.
Rule vs. Guidance Dichotomy.
Applying § 227.01(13), the majority held that the disputed communications lacked three classic hallmarks of a rule: (i) they imposed no new legal duty, (ii) violation could not directly trigger penalties, and (iii) they did not bind agency decision-makers—DNR would still have to prove in any enforcement action that PFAS meet the statutory criteria.
Section 227.10(1).
Because the PFAS statements are guidance, they are outside § 227.10(1). Moreover, the court crafted an additional doctrinal nuance: when an agency applies an unambiguous statute—as opposed to revising a prior interpretation—rulemaking is unnecessary.
Section 227.10(2m) and “Explicit Authority.”
Borrowing from Clean Wisconsin, the court found that § 292.01(5) and § 292.11 supply “broad but explicit” power to enforce discharge-reporting thresholds. Therefore, DNR did not violate the anti-implicit-authority provision.
Remedy.
Because WMC’s claims hinged on alleged “unpromulgated rules,” and the court found none, the proper course was to reverse and direct entry of judgment for the DNR.

c. Impact of the Decision

Environmental Regulation. DNR and similarly situated agencies can respond rapidly to emergent threats (e.g., PFAS, micro-plastics) without waiting years for rulemaking.
Administrative Procedure. The ruling narrows the circumstances under which agencies must undertake rulemaking, effectively elevating “guidance documents” as a flexible compliance tool.
Business Community. Regulated entities face greater uncertainty; they must monitor agency guidance and independently assess whether a substance on their site might meet statutory hazard criteria.
Litigation Forecast. Future challenges are likely to pivot from procedural (failure to promulgate) to substantive (does the substance actually meet statutory hazard criteria?). Courts may be called on more often to decide those fact-intensive disputes.
Separation-of-Powers Debate. The fiery dissent underscores a continuing ideological divide. Expect this case to be cited in future arguments over the constitutional limits of guidance vs. rule and the non-delegation doctrine.

4. Complex Concepts Simplified

Spills Law. A Wisconsin statute requiring anyone who discharges a “hazardous substance” to notify DNR immediately and clean it up.
Hazardous Substance (§ 292.01(5)). Any material that could harm people or the environment because of its nature, amount, or concentration. It is purposefully broad and covers future unknowns.
PFAS (“Forever Chemicals”). A family of ~9,000 synthetic compounds notable for persistence in the environment and links to health risks.
Rule vs. Guidance Document. A Rule is legally binding and enforceable; it must go through notice-and-comment rulemaking. Guidance expresses how an agency intends to apply existing law; it is not, by itself, enforceable.
§ 227.10(1) vs. § 227.10(2m).
• (1) mandates rulemaking when an agency adopts a policy/interpretation to govern enforcement.
• (2m) bars enforcement of any standard unless explicitly authorized by statute or rule. The court said the Spills Law is explicit enough.
Voluntary Party Liability Exemption (VPLE). A program letting property owners clean up contamination voluntarily to get a certificate shielding them (and future buyers) from liability.

5. Conclusion

The Wisconsin Supreme Court’s decision in Wisconsin Manufacturers and Commerce marks a significant recalibration of administrative-law boundaries in the state. By deeming DNR’s PFAS pronouncements mere guidance and not rules, the court strengthened agencies’ ability to act swiftly under broad statutory mandates, while simultaneously narrowing procedural avenues for regulated parties to challenge agency action on rulemaking grounds. The opinion’s articulation that “applying an unambiguous statute is not rulemaking” is poised to influence litigation well beyond environmental law, touching on taxation, professional licensing, and public health enforcement. Yet, as the dissent warns, the empowerment of executive agencies without parallel safeguards of formal rulemaking raises enduring questions about transparency, accountability, and the rule of law. Stakeholders—regulated entities, environmental advocates, and policymakers alike—will need to adapt to a landscape where guidance carries practical weight, and the onus of interpreting broad statutory language often falls on the regulated party pending judicial review.