Although deference is due to the agency's resolution of an ambiguous provision in the statute by clarifying that conditions outside of the mine escape must be considered in evaluating its compliance with the regulation, the agency's decision was not supported by substantial evidence, since no formal evaluation of the two escape routes in light of these criteria was conducted.
https://www.ca10.uscourts.gov/opinions/17/17-9541.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.