The EPA’s “Secret Science” rule establishing new standards for consideration of certain “pivotal” scientific studies, which was slated to go into effect on January 6, 2021, has been vacated and remanded by the U.S. District Court for the District of Montana. The decision follows one from a few days prior in which the court rejected EPA’s attempt to make the rule immediately effective. Notably, both decisions rely on the same basic principle — that the rule is not merely procedural, as EPA claimed, but substantive. That determination could be important for other rules that the Trump EPA viewed as procedural in nature, but that have been challenged as having substantive effect.