Federal Mine Safety and Health Review Commission Redefines Significant and Substantial Test September 19, 2025

The Commission redefined the Significant and Substantial (S&S) test, focusing on whether a violation could contribute to a hazard and whether the contribution is significant. This change matters because S&S designations are now more likely and easier to uphold. The core uncertainty is how this redefinition will affect enforcement outcomes at your operations.

Background

On September 19, 2025, the Federal Mine Safety and Health Review Commission announced a redefinition of the S&S test used in adjudicating mine safety violations Federal Mine Safety and Health Review Commission. Under the redefined test, the inquiry centers on whether a violation could contribute to a hazard and whether the violation makes a significant contribution to that hazard Safety Law Matters Federal Mine Safety and Health Review Commission. The Commission characterized the result as making S&S designations far more likely and easier to uphold on review Federal Mine Safety and Health Review Commission.

Key Provisions

• Effective action and date: The Commission redefined the S&S test on September 19, 2025, establishing the current framework for evaluating S&S designations in Commission proceedings Federal Mine Safety and Health Review Commission.
• Core elements of the redefined test: The analysis asks whether a cited violation could contribute to a hazard and whether the violation contributes significantly to that hazard Safety Law Matters Federal Mine Safety and Health Review Commission.
• Material enforcement impact: The Commission stated that S&S designations are now far more likely to be triggered under the redefined test Federal Mine Safety and Health Review Commission.
• Litigation posture: The Commission also stated that S&S designations are now easier to uphold when reviewed, altering the likelihood of sustaining S&S findings in contested matters Federal Mine Safety and Health Review Commission.

Decision Framework

Two threshold questions guide allocation decisions: (1) where do current conditions at your sites present hazards, and (2) where could any existing or foreseeable violations contribute to those hazards in a way that would be deemed significant under the redefined test Safety Law Matters Federal Mine Safety and Health Review Commission.

• If, at a given site, you identify violations that could contribute to a hazard, then the probability of an S&S designation has increased under the Commission’s redefinition, because S&S is now far more likely to be triggered and easier to uphold when those two elements are met Federal Mine Safety and Health Review Commission.
• If you are evaluating whether to prioritize categories like dust controls and mobile equipment guarding, then focus your assessment on whether potential violations in those categories could contribute to identifiable hazards and whether that contribution would be significant under the redefined test Safety Law Matters Federal Mine Safety and Health Review Commission.
• If your internal reviews show recurring issues where the two elements of the redefined test are likely satisfied, then the enforcement risk associated with those issues is elevated under the Commission’s stated approach that S&S designations are more likely and easier to sustain on review Federal Mine Safety and Health Review Commission.
• Before deciding, confirm: the specific hazards present at each site; which potential violations could contribute to those hazards; and where the contribution would plausibly be significant under the redefined test criteria Safety Law Matters Federal Mine Safety and Health Review Commission.

What We’re Monitoring

• Any official updates that clarify how the redefined S&S test will be applied in practice; we are watching the Commission’s news page for developments Federal Mine Safety and Health Review Commission.
• Subsequent legal analysis and practitioner commentary that interpret the redefined elements and application scenarios Safety Law Matters.
• Trends in S&S determinations in pending or future Commission matters following the September 19, 2025 redefinition Federal Mine Safety and Health Review Commission.