## Facts

- Congress enacted the Horse Protection Act to end “soring,” a practice using action devices (e.g., heavy chains) that can cause pain and produce a high-stepping gait in certain show horses.
- USDA issued regulations banning certain soring devices and broadly prohibiting devices that cause or could reasonably be expected to cause soring, while indicating it might adopt additional prohibitions if scientific evidence supported them.
- A university study identified devices used in the show-horse industry that were not prohibited by existing regulations but allegedly caused or risked causing soring.
- The American Horse Protection Association (AHPA) petitioned USDA to amend the regulations to ban the devices identified in the study.
- The Secretary of Agriculture denied the petition, stating that after reviewing the materials the Act was “best served” by maintaining existing regulations.
- AHPA sued in the U.S. District Court for the District of Columbia under the Administrative Procedure Act (APA); the district court granted summary judgment to the Secretary.
- AHPA appealed to the D.C. Circuit challenging reviewability and the adequacy of the denial’s explanation.

## Issues

1. Whether the Secretary’s refusal to initiate amendatory rulemaking in response to a petition is subject to judicial review or presumptively unreviewable as an exercise of enforcement discretion.
2. If reviewable, whether the Secretary’s denial of the rulemaking petition was arbitrary and capricious under the APA because the explanation was conclusory and failed to address material evidence and policy considerations.

## Decision

- The D.C. Circuit held that an agency’s denial of a petition for rulemaking is subject to judicial review.
- The court distinguished nonenforcement decisions (often presumptively unreviewable) from refusals to institute rulemaking, which occur within an APA framework expecting reasoned explanations.
- The court found USDA’s stated rationale for denying the petition insufficiently explained in light of the statute’s purpose and the evidence submitted.
- The court remanded with instructions for further proceedings so the matter could be returned to USDA for a more detailed explanation of the decision not to begin amendatory rulemaking.

## Legal Principles

- Denials of rulemaking petitions are generally reviewable under the APA and are not categorically shielded by the presumption against reviewability applicable to agency nonenforcement choices.
- A refusal to initiate rulemaking is evaluated under the APA’s “arbitrary and capricious” standard, with substantial judicial deference to an agency’s priority-setting.
- Even under deferential review, an agency must provide a reasoned explanation that addresses significant factual submissions and policy arguments raised by the petition, particularly where the agency previously suggested further regulation might be warranted if evidence emerged.
- A conclusory assertion that existing regulations “best serve” the governing statute may be inadequate when the petition presents technical or scientific material bearing on whether current rules fulfill statutory aims.

## Conclusion

The D.C. Circuit required USDA to give a materially fuller, reasoned explanation for refusing to initiate rulemaking under the Horse Protection Act, holding such denials reviewable under the APA and remanding because the agency’s initial explanation did not adequately address the petition’s evidence and statutory concerns.


Am. Horse Prot. Ass’n, Inc. v. Lyng, 812 F.2d 1 (D.C. Cir. 1987)