On September 19, 2025, the Federal Mine Safety and Health Review Commission issued a decision, Secretary of Labor v. Consol Pennsylvania Coal Company, that re-defined the interpretation of the “significant and substantial” (S&S) standard of Section 104(d) of the Federal Mine Safety and Health Act. The standard has undergone shifting interpretations over the decades. The Secretary did not request a review of the S&S test on appeal. However, the Commission’s decision revised the test to require only (1) a hazard to which the violation could contribute, and (2) that the violation significantly and substantially contributes to that hazard – making it substantially easier for the Secretary of Labor (and MSHA inspectors) to support and uphold S&S allegations. 

Scope of the S&S Standard: The S&S standard applies to all mine investigations and serves as a gateway for progressive enforcement. It can increase potential penalties, support a pattern of violations designation, and initiate the process toward a future withdrawal order or placement of an operator on a Pattern of Violation.

Key Takeaways from the Commission’s Decision

1. The Commission found the long-standing Mathies test unworkable. The test required four elements to determine whether a violation significantly and substantially contributed to the cause and effect of the hazard: (1) an underlying violation of a mandatory safety standard; (2) a discrete safety hazard contributed to by the violation; (3) a reasonable likelihood the hazard contributed to will result in an injury; and (4) a reasonable likelihood that the injury will be of a reasonably serious nature.
2. The Commission criticized Mathies’ steps 3 and 4 as unsupported by the text and noted ambiguities that led the Commission and federal courts to repeatedly alter the standard. A more recent Commission reformulation (articulated in Peabody Midwest Mining, LLC) required a showing that the hazard stemming from the violation was reasonably likely to cause an injury.
3. The Commission emphasized the text of 104(d)(1), which states that a S&S violation occurs when it “could significantly and substantially contribute” to a hazard. The D.C. Circuit’s decisions in Secretary of Labor v. Jim Walter Resources and Cumberland Coal Resources v. FMSHRC, which both held that only a contribution to the hazard was required, further reinforced the Commission’s interpretation. Additionally, the Commission found the tests from Mathies and Peabody encroached on the Mine Act’s separate “imminent danger” standard.

Moving Forward

The Commission’s decision lowers the S&S threshold. This shift in interpretation could result in increased S&S citations from MSHA inspectors.

Please reach out to a Husch Blackwell Workplace Safety & Health professional with any questions.

Fall Clerk Charlotte Rhoad also assisted with the drafting of this blog.