Overview
The Wisconsin Supreme Court heard argument on whether a Department of Natural Resources memorandum listing baseline air pollution values — the numbers a permit engineer plugs into dispersion modeling before deciding whether a proposed source will exceed ambient air quality standards — is an unpromulgated rule. The court of appeals held that it is, and ordered the Weston Generating Station permit reopened.1
The Department challenges a single element of the five-element definition: whether the protocol has the force of law. The argument reduced to a question this Court has never squarely answered. Can a binding method for finding facts carry legal force, or does only the standard the agency ultimately points to?
What You Should Know
Four things to carry into the decision
- Only one element is contested. The court of appeals found all five elements of Wis. Stat. § 227.01(13) satisfied and the parties conceded two below. On review the Department disputes force of law alone.2
- The timing matters. The court of appeals decided May 15, 2025. WMC v. DNR issued June 24, 2025. The panel did not have it, and a justice said so from the bench.3
- The Department asked the Court to adopt a “points to” test: what carries the force of law is the standard the agency points to as the basis for decision — here the promulgated numerical ambient standards — never the measurement that feeds the model.
- The Department’s best fact is the permit itself: eighty pages of conditions, none containing the background number. Sierra Club’s best fact is the preliminary determination, whose entire background analysis is one sentence and a hyperlink to the memo.
Method, or Substance?
Both sides agree the ambient air quality standards are promulgated rules. They disagree about what the memo that feeds them is.
A step removed from any legal determination
The protocol estimates a fact — the baseline pollution already in the air. The binding numbers are the promulgated ambient standards. Eighty pages of permit conditions contain no background number, no enforcement action has ever been brought on the memo, and an applicant is free to install its own monitors.
Content the statutes and rules do not supply
The protocol resembles WEPCO: it supplies content the statutes and rules do not, in mandatory terms directed at the official who decides the permit. The memo’s first page says the listed concentrations are the values to be used.
What Happened
The permit is for seven natural gas-fired engine units at the Weston Generating Station in Kronenwetter, Marathon County. Click any step for detail.
Values assigned statewide, by memo
The Department does not measure the baseline case by case. It publishes a protocol memorandum assigning values drawn from a regional monitoring network, sorted by whether a site is urban or rural. The first page states that the listed concentrations are the values to be used for air dispersion modeling as of its date.
One sentence and a hyperlink
In this permit, the Department’s entire written analysis of background pollution was one sentence and a hyperlink to the memo.
Sierra Club asks for site-specific monitoring
It commented that the assigned values, drawn in part from monitors in Iowa and Michigan and more than five years old, were not representative of air next to the interstate near Wausau. The Department declined and pointed back to the protocol.
Dane County rules for the Department
The Dane County Circuit Court (Remington, J.) ruled for the Department.
Court of appeals reverses in relevant part
District IV remanded with directions to reopen the permit.1
WMC v. DNR issues — after the panel ruled
The panel did not have it. A justice noted the sequence from the bench.3
Argument
Before the Wisconsin Supreme Court.
Sierra Club says the protocol resembles WEPCO: it supplies content the statutes and rules do not, in mandatory terms directed at the official who decides the permit. The Department says WMC controls and the protocol is a step removed from any legal determination.
Legal Background
A rule under Wis. Stat. § 227.01(13) is a regulation, standard, statement of policy or general order of general application, having the effect of law, issued by an agency to implement, interpret or make specific legislation it enforces or administers. All five elements must be met, and the definition excludes guidance documents and case-by-case permit determinations. Section 227.10(1) separately directs that each statement of general policy meeting the definition be promulgated as a rule.2
Two decisions frame the argument from opposite ends. In Wisconsin Electric Power Co. v. DNR, the Department translated a qualitative standard prohibiting substances toxic to aquatic life into specific numeric chlorine limits and applied them across permits; the limits were unpromulgated rules.4
In WMC v. DNR, the Court held that Department communications about PFAS were guidance documents lacking legal force, and identified the effect of law with sanctions, license denial, or legal effect on the interests of a class through enforcement.3
The definition reaches a standard governing the organization or procedure of an agency. A position that a fact can never carry the force of law has to explain why the legislature wrote that phrase at all.
Key Exchanges
Summarized from the argument rather than quoted. Speakers are identified as the argument record identifies them.
Noted that the definition of a rule reaches not only measures with the force of law but also those governing an agency’s organization or procedure, and asked whether a binding procedure for how an agency constructs facts in a given case could itself meet the definition.
Argued that no fact-finding and no methodology were applied in this permit, and that the protocol document was the beginning and the end of the background analysis.
Pressed that if a permit were struck down, the Department would point to the ambient air quality standards rather than the background memo — and asked how the memo therefore carries the force of law.
Answered with the practical consequence: a site in Kronenwetter is assigned a lower background value and clears the standard, while the same source across the street in Rothschild or South Wausau draws the higher value and does not — the number decides whether the permit issues.
Zoom In
The decisive moment came on rebuttal. Asked whether an agency can insulate anything from rulemaking by calling it guidance, counsel for the Department answered yes by definition, drew the obvious follow-up about governing by will regardless of what the legislature says, and immediately retreated: the label is not determinative, the substance is.
If substance controls, the Court cannot resolve this by classifying the document.
It has to decide whether a predetermined number that a permit engineer is directed to use is substance or method.
Justice Hagedorn supplied it. The definition reaches a standard governing the organization or procedure of an agency.
A position that a fact can never carry the force of law has to explain why the legislature wrote that phrase at all.
The Department’s structural case is real: eighty pages of enforceable conditions without the number, no enforcement action ever brought on the memo, and an applicant free to install its own monitors.
The last point wilted. Counsel conceded that validation requires two years of data, that applicants therefore almost never do it, and could say only that applicants have the option.
It identified no error in this permit, has no competing data, and does not contend the outcome would have differed.
That answer is legally correct and rhetorically weak, and it invites a disposition affirming the Department on this record without settling the doctrine.
What’s Next
The transcript records no participation by Justice Taylor, who sat on the panel below. Her recusal is not confirmed: the Court’s pending-cases table does not track non-participation.
Whether the Court adopts the “points to” formulation
The Department asked for it by name. Adopted, it would give agencies a clean and generous safe harbor for internal numeric tables of every kind, and it would be the most consequential thing the opinion does.
Whether the fact-versus-law question gets answered
A narrow disposition is available. A broad one would tell every agency in the state whether a mandatory internal methodology must go through rulemaking.
The § 227.10(1) alternative ground
Sierra Club argues it operates independently of the rule definition. Justice Hagedorn signaled skepticism. If the Court reaches it, it is the sleeper issue with the widest reach beyond air permitting.
Endnotes & Authorities · 4 citations
- Sierra Club v. Wisconsin Department of Natural Resources, 2025 WI App 39, No. 2024AP673 (Ct. App. May 15, 2025) (Kloppenburg, P.J., joined by Graham and Taylor, JJ.), reversing in relevant part the Dane County Circuit Court (Remington, J.), No. 2023CV2379. Review granted February 12, 2026; argued September 15, 2026.
- Wis. Stat. § 227.01(13) (definition of rule); § 227.10(1) (rulemaking directive); § 285.63(1)(b). The parties conceded elements (2) and (4) below.
- Wisconsin Manufacturers & Commerce, Inc. v. DNR, 2025 WI 26 (June 24, 2025) (Protasiewicz, J.; Hagedorn, J., concurring; R.G. Bradley, J., dissenting, joined by Ziegler, J.).
- Wisconsin Electric Power Co. v. DNR, 93 Wis. 2d 222, 287 N.W.2d 113 (1980); see also Service Employees International Union, Local 1 v. Vos, 2020 WI 67; Midwest Renewable Energy Ass’n v. PSC, 2024 WI App 34; Citizens for Sensible Zoning, Inc. v. DNR, 90 Wis. 2d 804, 280 N.W.2d 702 (1979) (five-element test); Frankenthal v. Wisconsin Real Estate Brokers’ Board, 3 Wis. 2d 249, 89 N.W.2d 825 (1958); Barry Laboratories, Inc. v. Wisconsin State Board of Pharmacy, 26 Wis. 2d 505, 132 N.W.2d 833 (1965) (the “points to” line of authority the Department relied on).