"The plaintiffs -- Republican attorneys general from 19 states, the Governor of Maine, and two individual plaintiffs from Texas -- sought a declaration (in Count I of their amended complaint) that the ACA's individual mandate was no longer constitutional because it no longer triggers a tax.... [T]he U.S. House of Representatives, under Democratic control as of January 3, submitted a motion to intervene in the litigation -- as to the plaintiffs' claims other than Count I.... The House acknowledged, however, that it cannot intervene as to Count I, because the intervenor states' notice of appeal to the Fifth Circuit means the district court can no longer grant intervention concerning Count I."