Ohio v. EPAThe Clean Air Act requires both the States and federal government to help develop environmental regulations.  When the EPA creates certain standards regarding air quality, states have to develop their own "State Implementation Plan," which requires States to both set out how to go about applying the federal regulations, and it also requires States to consider its impact on neighboring States (called the Good Neighbor Provision).  The EPA can step in when States won't comply with federal guidelines in creating their plan.  Some State plans were not approved, and 12 States obtained a stay of enforcement of these denials.  This changes the numbers for either State -- becasue part of the benefit of multiple States coming together is the economies of scale of implementation.  Ohio, and some other States, now are trying to obtain a stay of the EPA's decision to implement a federal plan, alleging that implementation is arbitrary or caprcicious, given that so many other States are now out of the plan.  The main issue of the four factors to determine whether to grant a stay, according to the Court, is which side is likely to prevail on the merits.  The Court held that the stay is granted pending review from the D.C. Circuit.  Gorsuch delivered the opinion of the Court, in which Roberts, Thomas, Alito, and Kavanaugh joined.  Barrett filed a dissenting opinion, which was joined by Sotomayor, Kagan, and Jackson.