Seventh Circuit Rule 52 allows the U.S. Court of Appeals for the Seventh Circuit, when faced with “questions arising under the laws of [a] state which will control the outcome of a case pending in the federal court” to “certify such a question to the state court in accordance with the rules of that court” and to “stay the case . . . to await the state court’s decision.”
The Seventh Circuit has explained in Cleary v. Philip Morris Inc. that certification of a question of state law is appropriate only if the court is “genuinely uncertain about a question of state law that is vital to a correct disposition of the case.” 656 F.3d 511, 520 (7th Cir. 2011).
Don’t confuse “novel” or “unresolved” with “genuinely uncertain,” however. Federal courts frequently answer questions of state law in the absence of controlling authority—making what is sometimes referred to as an “Erie guess.” (Erie Railroad Co. v. Tompkins is the landmark decision issued by the Supreme Court in which it required federal courts to apply the law of the state’s highest court when hearing state-law claims under their diversity jurisdiction. 304 U.S. 64 (1938).)
The Seventh Circuit’s recent decision in In re: Zimmer NexGen Knee Implant Products Liability Litigation, No. 16-3957 (7th Cir. 2018), written by Judge Diane Sykes, is illustrative of the standard and the high bar for certification.