This is a climate case based on public nuisance and misrepresentation. Defendants removed to federal court under the federal officer statute and the Circuit sent it back. Defendants appealed to the USSC, which accepted cert. and rule that when the federal officer statute was triggered, the appeals court had a duty to remand to consider all grounds for removal.
Scotus Blog – Case preview: Justices to consider procedural issue in major climate-change lawsuit