Whether a federal court may sua sponte raise a procedural affirmative defense to deny preliminary injunctive relief without considering the movant's likelihood of success on the merits

Mr. Pye brought an action pursuant to 42 U.S.C. §1983 and contemporaneously sought a temporary restraining order or preliminary injunction to restrain Respondents from pursing his execution. He filed this constitutional challenge just days after learning that Respondents planned to execute him without any of the notice and critical procedural protections that they have accorded to another group of identically situated death-sentenced persons in Georgia, in violation of the Equal Protection and Due Process clauses. In opposing Mr. Pye’s emergency motion for a stay of execution before the Eleventh Circuit, Respondents argued only that Mr. Pye was unlikely to succeed on the merits of his underlying constitutional claims. They raised no procedural or other defenses. Nevertheless, the Eleventh Circuit swa sponte injected the consideration of an inapposite procedural principle and ruled that Mr. Pye was not entitled to a stay because “res judicata likely bars his federal complaint.” Therefore, the question presented is: Whether a federal court may raise a procedural affirmative defense swa sponte in the absence of any special circumstances, and, if so, whether it may do so to deny preliminary injunctive relief without otherwise considering the movant’s likelihood of success on the merits?