Is the Once in, Always in Policy Finally Dead?
By Ethan R. Ware
EPA’s controversial “Once in, always in, Rule” (Once in Rule) was recently rescinded under the Congressional Review Act, a statute which gives Congress the authority to overturn agency rules if such action is taken within specified time frames after the rules is adopted. A joint resolution Congressional resolution disapproving the rule, adopted by both the Senate and the House, was signed into law by President Trump on June 20, 2025. Sources of hazardous air pollutants (HAPs) may once again voluntarily install air control technology or adopt production limits to reclassify as “area sources” and avoid installing more expensive air pollution control technology necessary for “major sources” of HAPs. Moreover, because the rule was disapproved under the CRA, Congressional approval will now be required for a similar rule to be adopted by EPA in the future.
Clean Air Act Permitting Scheme
The Clean Air Act (Act) establishes a system of progressively more complete and comprehensive air emissions controls depending on the amount and hazardousness of a facility’s emissions. The more comprehensive, more expensive controls apply to “major sources” of HAPs, while less complex and less expensive controls apply to “area sources,” which emit less than 10 tons per year of an individual HAP and less than 25 tons per year of all HAPs. 40 CFR 63.1 (a)(1)-(3).
The “Once In, Always In” Policy
The original "once in, always in" policy by the EPA mandated that facilities classified as major sources of HAPs would remain under stringent regulations even if their emissions fell below the major source thresholds. The "once in, always in" policy was established in 1995 by EPA under Act, stating that once a facility became a major source of HAPs, it would always be classified as such, regardless of any reductions in emissions. This interpretation of the Act was not promulgated as a rule, but rather was seen by EPA as a policy required by the terms of the Act.
Changes to the Policy
When the EPA in the first Trump administration considered the “once in, always in” policy, it issued guidance in 2018 and subsequently adopted a rule in 2020 that struck the policy down as a violation of a plain, simple reading of the Clean Air Act. “Today’s memo finds that EPA had no statutory authority under the Clean Air Act to place a time limit on when a facility may be determined to be an area source, and that a plain language reading of the Act must allow facilities to be reclassified as area sources once their potential to emit hazardous air pollutants falls below the levels that define major sources.” See here. Therefore, under the first Trump administration EPA, major sources were able to voluntarily reduce compliance burdens by reclassifying as area sources through the addition of air emission control technology or restrictions on production rates such that air emissions remain below major source thresholds.
The Once in Policy Reinstituted as a Rule
Not surprisingly, the Biden EPA reversed course and the “once in, always in” concept was promulgated as regulation, undoing the effect of the prior 2020 rulemaking. The Once in Rule was finalized in the waning days of the Biden Administration to stop industries from reducing emissions to avoid the enhanced technology required of major sources. 89 Fed. Reg. 73293 (Sept. 10, 2024). “This action amends the General Provisions of 40 CFR part 63 to require sources subject to certain major source NESHAP subparts to remain subject to those NESHAP regardless of whether they reclassify to area source status.” 89 Fed. Reg. at 73298. This was the case even if the facility later voluntarily adopted innovative technology or production limits to get below the major source threshold. Id.
The Once in Rule was not unlimited, however. It only applied to sources subject to MACT standards for seven specific persistent and bio-accumulative pollutants. The seven pollutants in question are: Alkylated lead compounds, Polycyclic organic matter (POM), Mercury, Hexachlorobenzene, Polychlorinated biphenyls (PCB), 2,3,7,8-tetrachlorodibenzofurans (TCDF), and 2,3,7,8-tetrachlorodibenzo-p-dioxin.
Review of the Once in Rule
Under Section 801(d) of the CRA, any regulation submitted to Congress either less than 60 days of session in the Senate or less than 60 legislative days in the House of Representatives before Congress adjourns a session of Congress sine die, begins a new period for congressional review of that rule becomes available in the next session of Congress. That is the case with the Once in Rule, since it passed so late in the Biden Administration. The Senate resolution disapproving the rule passed on May 1, 2025, the House resolution was adopted on May 22, 2025, and the resolution was signed by the President on June 20, 2025.
Conclusion: Next Steps
Due to this Congressional action the 2020 regulation adopted under the first Trump administration remains in effect and industry will be free to explore innovative ways to extricate itself from the more complex air technology requirements of the MACT regulations. In addition, as noted above, any rule reinstating the “once in, always in” concept would first have to be authorized by Congress. This means the days of the policy as a regulatory football are likely at an end.
Agencies Propose Revision to the Endangered Species Act “Harm” Definition
By Tanner N. Brantley
The U.S. Fish and Wildlife Service (FWS) and National Marine Fisheries Service (NMFS) (collectively referred to as the “Agencies”) proposed on April 17, 2025, to remove the definition of “harm” under their respective regulations promulgated pursuant to the Endangered Species Act (ESA) (the “ESA Regulations”). The comment period for this proposed rulemaking closed on May 19, 2025, generating approximately 357,500 comments submitted to the Agencies. The Agencies took this action after determining that the current definition of “harm,” which includes habitat modification degradation, goes beyond and, therefore, contradicts the “well-established, centuries-old understanding of ‘take’ as meaning to kill or capture a wild animal.” The Agencies found support for this action as well in the United States Supreme Court’s recent decision in Loper Bright v. Raimondo, 603 U.S. 369, 400, 144 S. Ct. 2244, 2266 (2024).
“Take” under the Endangered Species Act
The ESA prohibits the “take” of endangered species.16 U.S.C. 1538(a)(1)(B)-(C). The ESA defines “take” to means “harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct.” 16 U.S.C. 1532(19). The term “harm” used in this definition is not defined by the ESA itself, but it is defined in the ESA regulations as “an act which actually kills or injures wildlife,” such as “significant habitat modification or degradation where it actually kills or injures wildlife by significantly impairing essential behavioral patterns, including breeding, feeding or sheltering.” 50 CFR 17.3 “Harm.”
In the Wake of Loper Bright
Loper Bright overturned long-standing doctrine established in the Court’s decision in Chevron, U.S.A., Inc. v. NRDC, Inc., 467 U.S. 837, 104 S. Ct. 2778 (1984) by which federal courts granted deference to an agency’s interpretation of ambiguous statutory language if that interpretation could be found to be a reasonable one. The Agencies stress that the Supreme Court relied upon Chevron when it upheld the “harm” definition in Babbitt v. Sweet Home Chapter of Communities for a Great Oregon, 515 U.S. 687, 115 S. Ct. 2407 (1995). The Court in Babbitt stated the central question of the case was whether the Agencies exceeded their authority under the ESA by promulgating a regulation that included habitat modification in the definition of “harm.” Babbitt, 515 U.S. at 690. The challengers in that case argued then the Secretary on the Interior had exceeded his authority and that the “harm” definition should have been limited to “direct applications of force against protected species.” Id. at 697. Nonetheless, the Babbitt Supreme Court determined the Secretary of the Interior had not exceeded his authority under the ESA, finding that the inclusion of the definition of “harm” was a reasonable interpretation of ambiguous ESA statutory language consistent with the Chevon doctrine. Accordingly, it upheld the inclusion of "significant habitat modification or degradation where it actually kills or injures wildlife" in the definition of “harm.” Id. at 708.
Agencies’ Rational for Removal of the “Harm” Definition
The Agencies acknowledge in the proposed rule that the Supreme Court’s holding in Babbitt has validated the “harm” definition for thirty years but stress that the overturning of Chevron compels reassessment of the definition. The Agencies note the Loper Bright opinion clarified that the proper questions to ask on review of an agency regulation when resolving such ambiguities are “whether the statute authorizes the challenged agency action,” and if the regulation matches the single, best meaning of the statute. 90 Fed. Reg. 16102, 16103. The Agencies in turn contend the current definition of “harm” in the ESA regulations that was upheld in Babbitt does not actually reflect the single, best meaning of a “take” under the ESA and therefore should be rescinded.
The Agencies refer to the Babbitt’s Court’s reliance on the now overturned Chevron doctrine and Justice Scalia’s dissent in Babbitt as justifications for the recission. Indeed, the proposed rule echoes two arguments made by Justice Scalia in his dissent. The first argument is that the term "take" as applied to wild animals means to reduce those animals to human control by killing or capturing them. The second is that the noscitur a sociis canon of statutory construction was properly employed by the Court of Appeals during the Babbitt appeal process, even though the Babbitt Supreme Court found otherwise. (Noscitur a sociis is a canon of statutory construction in which the meaning of an unclear or ambiguous word is determined by “gather[ing] meaning from the words around it.” Babbitt at 702.) The Agencies quoted Justice Scalia in the proposed rule and stated the definition of harm should be interpreted like the other verbs in the “take” definition and require an “affirmative act[ ] . . . directed immediately and intentionally against a particular animal—not [an] act[ ] or omission[ ] that indirectly and accidentally cause[s] injury to a population of animals.” Babbit at 719-20.
Next Steps and Implications for Regulated Parties
Although the Agencies state they do not intend to propose a new definition for “harm,” after the Agencies finish reviewing the public comments, they will confirm whether they will proceed with the original proposed rule, issue a new or modified proposed rule, or withdraw the proposed rule. The Agencies emphasize that the proposed recission, if finalized, would not impact permits that have been granted as of the date the recission becomes final.
Any entities with future or currently pending projects that may impact an endangered or threatened species habitat, indirectly or directly, should evaluate the implications the proposed rule may have on any potential habitat-related concerns and regulatory obligations. If the proposed rule is finalized, projects with pending permits as of the date the proposed recission becomes final should consider the possibility of permitting delays or altered regulatory obligations in the event the final rule is appealed. Finally, even though the proposed recission of the definition may limit the scope of species protection provided by the current ESA regulations as to habitat modification, habitats may still be protected at the state or local level. Regulated parties should therefore continue to assess whether any state or local requirements may be applicable to habitat impacts even if the definition of “harm” is rescinded as proposed.
On a related note, on June 9, 2025, FWS published a request for information and comments to improve the overall efficiency and effectiveness of the permitting program under section 10(a) of the ESA. That comment period closed on July 9, 2025.
TSCA Test Marketing Exemption for New Chemicals: A Recent Case Study
By Ryan W. Trail
On July 24, 2025, U.S. Environmental Protection Agency (EPA) approved a Test Marketing Exemption (TME) under section 5(h)(1) of the Toxic Substances Control Act (TSCA) for a confidential new chemical substance (TME Application No. T-24-0001). While the specific identity of the chemical remains protected as confidential business information, the Federal Register notice outlines key criteria of the exemption, which provide a helpful refresher for chemical companies considering testing market conditions for a new chemical.
A TME allows a manufacturer to introduce a new chemical into commerce for a limited test marketing period without the regulatory burden of undergoing TSCA Premanufacture Notification (PMN), a cumbersome process by which EPA thoroughly evaluates risks associated with new chemicals prior to introduction into commerce. The purpose of the TME is to first allow companies the opportunity to evaluate customer interest and performance in realistic market settings.
In approving TME Application No. T-24-0001, the EPA concluded that the proposed use - manufacture and use as a raw material in the production of esters - did not pose unreasonable risk, based on review of available health and environmental data. The exemption includes several conditions typical of TMEs. The company is limited to producing no more than 50 tons of the substance per year. The exemption is effective for a period of 365 days, beginning with the first date of manufacture. The chemical must be fully consumed during its intended use. Each shipment must be accompanied by a bill of lading stating that its use is limited to those approved by the TME. The manufacturer must maintain records for at least five years, including production quantities, shipment dates and destinations, and copies of associated shipping documents. Importantly, the EPA retains the authority to modify or revoke the exemption if new information suggests the chemical may present an unreasonable risk.
For companies contemplating a TME, the regulatory pathway offers an opportunity to explore market potential while deferring the time and expense of full PMN review. However, applicants must be prepared to submit detailed information upfront, including health and environmental effects data, projected production volume, number and identity of customers, exposure scenarios, marketing plans, and safety data sheets. Deviations from approved terms, such as exceeding volume cap or distributing to unapproved recipients, could result in enforcement or revocation of the exemption.
This latest TME approval provides a clear example of the EPA’s expectations for test marketing under the TSCA exemption. While the process offers flexibility for early-stage market exploration, it comes with strict conditions and oversight. Companies considering a TME should prepare thoroughly, maintain complete documentation, and remain vigilant in complying with all recordkeeping requirements.
Everything Old is New Again: Actual Emissions are No Longer Enforceable Under NSR Permitting
By Ethan R. Ware
EPA is withdrawing the proposed rule titled ‘‘Prevention of Significant Deterioration (PSD) and Nonattainment New Source Review (NNSR): Regulations Related to Project Emissions Accounting’’ published in the Federal Register on May 3, 2024. 90 Fed. Reg. 34206 (July 21, 2025). The decision to reverse enforcement of “actual emissions” as permitted limits over those established by permit at new source review (NSR) major sources (“2025 NSR Project Policy”) relieves industry of unauthorized emissions restrictions.
NSR Permitting: Existing Facilities
NSR permitting is a Federal permitting program applicable to construction of a “major source.” Of course, this includes projects that are new construction and modifications at existing facilities: an existing major stationary source triggers NSR permitting when it undergoes a ‘‘major modification,’’ while new sources trigger NSR when a new source itself exceeds the major source threshold. NSR permitting triggers the addition of “best available control technology” (BACT) or controls that meet “lowest achievable emissions rates” (LAER), depending on where a project or new stationary source is located.
The thresholds for triggering “major” emissions levels are different for existing sources and new construction. An existing source modification is considered major when emissions of certain listed pollutants (e.g., VOCs) exceed defined levels, which by rule cause a “significant emissions increase,” typically less than 40 tons per year (tpy). 40 CFR 52.21(a)(2). A new construction must itself qualify as a major source to trigger NSR permitting, including having potential to emit more than the “major source levels” assigned to the type of industry—typically 100 to 250 tpy. Id.
Regulations establish a two-step process for determining emissions for new “projects” at “existing stationary sources.” To be subject to major NSR requirements at those facilities, the proposed project must result in both (1) a significant emissions increase from the project (the determination of which is called ‘‘Step 1’’ of the NSR applicability analysis); and (2) a significant net emissions increase across the entire stationary source, taking into account emission increases and emission decreases attributable to other projects undertaken at the stationary source within a specific time frame (called ‘‘Step 2’’ of the NSR applicability analysis, or ‘‘contemporaneous netting’’). Id.
Of course, the baseline emissions against which a project is measured become important to determining significant emissions increases under step 1. Under the “Project Emissions Accounting Rule” in place in 2020, 85 Fed. Reg. 74890, “both increases and decreases resulting from a project shall be accounted for under Step 1 of the NSR applicability process….” 90 Fed. Reg. at 34206. This is because according to EPA “a full accounting of emissions changes resulting from a project is more consistent with the definition of ‘’modification’ [under the Clean Air Act,] Section 111(a)(4).” Id.
In 2024, the Biden EPA proposed to revise the definition of ‘‘project’’ such that “decreases accounted for under the Step 1 significant emissions increase calculation [become] enforceable” emissions limitations (typically much less than listed permit values), thereby reducing the baseline against which the “significant emissions increase” for projects is measured and the potential maximum emissions of a new project or modification. 89 Fed. Reg. 36870 (May 3, 2024). The result is potential emissions from such projects at existing facilities will be less than otherwise allowed. 90 Fed. Reg. at 34206.
2025 NSR Project Policy
The 2025 NSR Project Policy reverses the 2024 emissions-counting rules. As a result, fewer projects at existing facilities will trigger NSR permitting.
By the 2025 NSR Project Policy, EPA is reversing the 2024 guidelines and regulations. “Regarding the EPA’s proposal to make decreases in emissions accounted for in the Step 1 significant emissions increase calculation enforceable, commenters demonstrated that the rationale for this part of the proposal is inconsistent with the EPA’s rationale (reflected in prior NSR rulemakings) for other provisions in the EPA’s NSR regulations, and that implementation of this part of the proposal would restrict source operation for projects that involve projected decreases in emissions.” 90 Fed. Reg. at 34207. In a 2002 final rule, EPA had made quite clear “projected actual emissions should not be made enforceable through a permitting action, [because] doing so…may place an unmanageable resource burden on reviewing authorities.” 67 Fed. Reg. 80186, 80204 (December 31, 2002).
“This same reasoning applies regardless of whether a projection results in an increase or decrease in emissions, and the EPA did not receive any comments on the proposal that provided a compelling basis for requiring an enforceable limitation in one instance but not the other.” 90 Fed. Reg. at 34207-208.
Conclusion
The 2025 NSR Project Policy is a return to a more refined characterization of EPA permitting authority for NSR sources under the Clean Air Act. In sum, the NSR permittee need not consider actual emissions in calculating the floor of “project” emissions for purposes of determining whether a new project causes a significant emission increase of regulated pollutants at an existing source.
