Does Younger apply when a federal claim is derivative of a claim that could be brought in ongoing state court proceedings or does Younger also require inevitable direct interference with state judicial proceedings?

QUESTION PRESENTED In 1990, Arizona voters amended the Arizona Constitution to include the Victims’ Bill of Rights. See Ariz. Const. art. II, §2.1. Arizona then passed the Victims’ Rights Implementation Act, providing, in part, that a “defendant, the defendant’s attorney or an agent of the defendant shall only initiate contact with the victim through the prosecutor’s office.” Ariz. Rev. Stat. §13-4433(B) (the “Statute”). Decades later, Respondents (a membership organization, criminal-defense attorneys, and an investigator) allege that the Statute violates their own First Amendment rights, not the rights of their clients, and seek injunctive and declaratory relief preventing enforcement of the Statute in state court criminal proceedings. In Younger v. Harris, 401 U.S. 37 (1971), this Court held that federal courts are prohibited from enjoining ongoing state criminal proceedings. The Court later applied “Younger abstention” where a federal claim is derivative of a claim that could be litigated in ongoing state proceedings. The circuits have split, however, on the standard to be used when applying Younger abstention to such derivative claims. Below, the Ninth Circuit rejected Younger abstention because “the plaintiffs’ interests are not ‘so intertwined’ with those of their clients in state court proceedings that ‘interference with the state court proceeding is inevitable.” Does Younger apply when a federal claim is derivative of a claim that could be brought in ongoing state court proceedings or does Younger also require inevitable direct interference with state judicial proceedings?