In a move that surely caused money to change hands between law nerds gambling on federal rules interpretations through off-shore gambling sites, the United States Supreme Court held, in Nutraceutical Corp. v. Lambert (February 26, 2019), that Fed. R. Civ. P. 23(f) — the portion of Rule 23 that permits parties to request permission for interlocutory review of class certification decisions within 14 days of the issuance of the decision — is a mandatory, but nonjurisdictional, claim-processing rule, and therefore not subject to tolling or other exceptions for reasons of equity or fairness. The decision was unanimous.