LOKEN, Circuit Judge.

Russell Bucklew was convicted in state court of murder, kidnapping, and rape and sentenced to death. After Missouri courts denied post-conviction relief, we affirmed the district court's denial of Bucklew's petition for a federal writ of habeas corpus. Bucklew v. Luebbers, 436 F.3d 1010, 1013-15 (8th Cir.2006). This appeal concerns his § 1983 challenge to Missouri's lethal injection method of execution.

I.

On April 9, 2014, the Supreme Court of Missouri issued a writ of execution, setting Bucklew's execution date as May 21, 2014. At that time, Bucklew was a plaintiff in a pending § 1983 action that included a facial Eighth Amendment challenge to Missouri's method of execution. The district court tentatively dismissed that action on May 2. Zink v. Lombardi, No. 12-04209 (W.D.Mo. May 2, 2014). Bucklew filed this § 1983 action on May 9, primarily asserting that the method of lethal injection by which Missouri plans to execute him would violate his Eighth Amendment right to be free of cruel and unusual punishment because of the unique risk that his serious medical condition, called cavernous hemangioma, will result in excruciating pain. He also sought a preliminary injunction and a stay of execution.

On May 16, the district court entered a final order dismissing the complaint in Zink. Plaintiffs including Bucklew appealed. On May 19, the district court entered the Order being appealed in this action, denying Bucklew's motion for a stay of execution and an injunction and dismissing the Eighth Amendment claim, sua sponte. Bucklew v. Lombardi, No. 14-8000, 2014 WL 2736014 (W.D.Mo. May 19, 2014). Bucklew appealed, raising Eighth Amendment and due process issues, and sought a stay of the May 21 execution.1 A divided panel of this court granted a stay. Bucklew v. Lombardi, 565 Fed.Appx. 562 (8th Cir.2014). The court en banc vacated the panel's stay and denied a stay of execution. Bucklew then applied to the Supreme Court for a stay of execution. On May 21, the Supreme Court issued an amended order:

After the Supreme Court granted a stay pending appeal, we granted initial en banc review of Bucklew's appeal and the appeal in Zink and scheduled both cases for argument on September 9. After the oral arguments, we concluded that Bucklew's "as applied" Eighth Amendment claim warrants a separate opinion. His due process claim is not materially different than the due process claim raised in Zink and will be resolved in our opinion in that case.

II.

In resolving an earlier appeal in Zink, we applied the Supreme Court's plurality opinion in Baze v. Rees, 553 U.S. 35, 50, 128 S.Ct. 1520, 170 L.Ed.2d 420 (2008), and ruled that, to state an Eighth Amendment method-of-execution claim, a plaintiff must plausibly allege a substantial risk of severe pain, and "a feasible and more humane alternative method of execution, or a purposeful design by the State to inflict unnecessary pain." In re Lombardi, 741 F.3d 888, 895-96 (8th Cir.) (en banc), reh'g denied, 741 F.3d 903 (8th Cir.), cert. denied, ___ U.S. ___, 134 S.Ct. 1790, 188 L.Ed.2d 760 (2014). When the Zink plaintiffs subsequently declined to amend their complaint to allege a more humane alternative, the district court dismissed their facial Eighth Amendment challenge to Missouri's lethal injection protocol. That was the primary focus of plaintiffs' Eighth Amendment appeal in Zink.

In the Order being appealed, after denying Bucklew a preliminary injunction and stay of execution, the district court dismissed the complaint. The court first concluded that the expert affidavits Bucklew submitted in support of his motion for stay of execution to show a substantial likelihood of needless pain "do not contain the specificity necessary to prevail on an Eighth Amendment claim." That was a merits analysis appropriate in ruling on a motion for summary judgment, not an analysis of whether the complaint plausibly pleaded an Eighth Amendment claim under Baze and Lombardi. However, the court went on to conclude that the complaint must be dismissed because Bucklew had not alleged that a "feasible and readily available alternative" method of execution exists, and because plaintiffs in Zink, including Bucklew, had declined to amend their complaint to allege such an alternative. That was a properly focused Rule 12 analysis of the pleading.

On appeal, Bucklew argues, like appellants in Zink, that our decision in Lombardi misinterpreted the Supreme Court's decision in Baze. We will resolve that issue in our separate en banc opinion in Zink. But Bucklew primarily argues that our rule in Lombardi does not apply to his separate § 1983 action, or alternatively that he meets the requirements of that rule, because he has adequately alleged that Missouri's method of execution if applied to him would, because of his unique medical condition, violate the Eighth Amendment standard — a "substantial risk of serious harm," Baze, 553 U.S. at 50, 128 S.Ct. 1520 (plurality opinion) — and a readily available alternative that would significantly reduce the risk.

Between our decision in Lombardi on January 24, 2014, and the order staying Bucklew's execution pending this appeal, the Supreme Court denied last minute stays of execution to four Zink plaintiffs, most of whom argued that our decision in Lombardi misconstrued Baze and therefore warranted stays of execution. The Supreme Court did not grant Bucklew a stay of execution, but it did grant a stay pending appeal, which had the same immediate effect. The Court's decision to grant a stay pending appeal reflected its determination that Bucklew had shown "a significant possibility of success on the merits" of his appeal from the district court's dismissal of his complaint. Hill v. McDonough, 547 U.S. 573, 584, 126 S.Ct. 2096, 165 L.Ed.2d 44 (2006). Consideration of why the Court concluded that Bucklew's challenge to Missouri's lethal injection method of execution might be so significantly different requires a close look at the record on appeal.

III.

We first quote portions of our prior panel opinion describing the allegations in Bucklew's complaint and the opinions of his medical experts regarding the medical condition on which his as-applied challenge is based:

Without filing a response to Bucklew's complaint, defendants filed Suggestions in Opposition to his motions for a preliminary injunction and stay of execution. In arguing that Bucklew's showing was untimely and inadequate to warrant a stay of execution, defendants noted that Bucklew had urged that Missouri should not use methylene blue to flush the IV lines in his execution and stated: "The Department of Corrections will not use methylene blue in Bucklew's execution and will not use indigo carmine, a dye which also may raise blood pressure, or any other dye." Defendants did not explain what alternative procedure would be used to perform the dye's intended function. Defendants further stated:

In his Reply, Bucklew complained that defendants "have changed their executions procedures twice in forty-eight hours":

Despite this factual record, which went well beyond the four corners of Bucklew's complaint, the district court dismissed the complaint, sua sponte, because it did not contain the "plausible allegation of a feasible and more humane alternative method" that Lombardi required, and because plaintiffs' refusal to amend their complaint in Zink demonstrated that "affording Bucklew an opportunity to amend his pleading to state a known and feasible alternative would be futile." Without question, a district court has the power to dismiss a complaint sua sponte, but only where plaintiff cannot possibly prevail and amendment would be futile. See Smith v. Boyd, 945 F.2d 1041, 1042-43 (8th Cir. 1991). Here, we conclude the district court exercised this limited authority prematurely because it was not "patently obvious the plaintiff could not prevail." Id. at 1043.

There is case law supporting Bucklew's assertion that his as-applied challenge to Missouri's method of execution distinguishes his claim from the facial challenge in Zink. See Siebert v. Allen, 506 F.3d 1047, 1050 (11th Cir.2007). Defendants in responding to Bucklew's motions acknowledged his serious medical condition and stated that the Department's lethal injection procedure would be changed on account of his condition by eliminating the use of methylene blue dye. This concession bolstered the detailed allegations in Bucklew's complaint of a substantial risk of serious and imminent harm that is sure or very likely to occur, allegations far more specific than the allegations addressing this part of the Baze standard in the second amended complaint in Zink. Defendants' concession also tended to support Bucklew's detailed allegations that the State had unreasonably refused to change its regular method of execution to a "feasible, readily implemented" alternative that would "significantly reduce" the substantial risk of pain. Baze, 553 U.S. at 52, 128 S.Ct. 1520. At a minimum, it should have warned the court not to assume that Bucklew would decline an invitation to amend the as-applied challenge in his complaint simply because the Zink plaintiffs had declined to amend the very different facial challenge in their complaint.

For these reasons, we conclude the district court erred in dismissing the complaint, sua sponte. In our view, the entire record before the district court resembled the facts before the Supreme Court in Nelson v. Campbell, 541 U.S. 637, 124 S.Ct. 2117, 158 L.Ed.2d 924 (2004): Plaintiff alleged that the State would violate the Eighth Amendment by using a pre-execution "cut-down" procedure to reach his severely compromised peripheral veins. Defendants, while asserting that the purported § 1983 claim was barred by the successive habeas rule, acknowledged that plaintiff had proposed an alternative procedure that was a preferred method. After concluding that the case must be remanded because the claim was cognizable under § 1983, the Court noted: "An evidentiary hearing will in all likelihood be unnecessary, however, as the State now seems willing to implement petitioner's proposed alternatives." Id. at 646, 124 S.Ct. 2117. The record in this case differs because Bucklew's attorneys have given no indication they would compromise any of their demands. Indeed, some of those demands appear to be "relief [that] would foreclose execution," which would make his § 1983 claim non-cognizable. Hill, 547 U.S. at 582, 126 S.Ct. 2096; see Nelson, 541 U.S. at 648, 124 S.Ct. 2117. But the State's concession that it would alter its procedure by not using methylene blue dye brought Bucklew's claim at least potentially within the purview of Baze and therefore made pre-answer sua sponte dismissal of the complaint inappropriate.

IV.

On remand, the district court in addressing the merits of Bucklew's claim must proceed from the premise that "a State retains a significant interest in meting out a sentence of death in a timely fashion." Nelson, 541 U.S. at 644, 124 S.Ct. 2117. Thus, further proceedings should be narrowly tailored and expeditiously conducted to address only those issues that are essential to resolving Bucklew's as-applied Eighth Amendment challenge. "The District Court will have the usual authority to control the order of proof, and if there is a failure of proof on the first element that it chooses to consider, it would not be an abuse of discretion to give judgment for [defendants] without taking further evidence." Helling v. McKinney, 509 U.S. 25, 35, 113 S.Ct. 2475, 125 L.Ed.2d 22 (1993).

The first step should be a timely response by defendants to the complaint or any amended complaint. The parties' respective positions can then be clarified before determining whether discovery and an evidentiary hearing are needed. Bucklew's arguments on appeal raise an inference that he is impermissibly seeking merely to investigate the protocol without taking a position as to what is needed to fix it. He may not be "permitted to supervise every step of the execution process." Whitaker v. Livingston, 732 F.3d 465, 468 (5th Cir.), cert. denied, ___ U.S. ___, 134 S.Ct. 417, 187 L.Ed.2d 274 (2013); see Lombardi, 741 F.3d at 895. Rather, at the earliest possible time, he must identify a feasible, readily implemented alternative procedure that will significantly reduce a substantial risk of severe pain and that the State refuses to adopt. "[C]apital punishment is constitutional. It necessarily follows that there must be a means of carrying it out." Lombardi, 741 F.3d at 895, quoting Baze, 553 U.S. at 47, 128 S.Ct. 1520. Any assertion that all methods of execution are unconstitutional does not state a plausible claim under the Eighth Amendment or a cognizable claim under § 1983.

Now that the claim is being addressed on the merits, past delays bring to the forefront the question of the applicable statute of limitations governing method-of-execution Eighth Amendment claims, a question this court has not addressed. See Wellons v. Comm'r, Ga. Dep't of Corr., 754 F.3d 1260, 1263-64 (11th Cir.2014); Walker v. Epps, 550 F.3d 407 (5th Cir.2008), cert. denied, 558 U.S. 829, 130 S.Ct. 57, 175 L.Ed.2d 45 (2009); Cooey v. Strickland, 479 F.3d 412, 416-24 (6th Cir.2007), cert. denied, 553 U.S. 1014, 1006, 128 S.Ct. 2047, 170 L.Ed.2d 811, 796 (2008). A motion Bucklew filed in camera with this court more than eight years ago may suggest that his as-applied Eighth Amendment claim could have been asserted against any lethal injection protocol, not just the modified protocol adopted in October 2013.

Because this decision, when final, terminates Bucklew's appeal to this court, the Supreme Court's stay pending the appeal will expire of its own terms. The writ of execution has also expired, though of course a new writ may issue. Thus, we leave to the discretion of the district court whether a temporary stay pendente lite may be needed. See Hill, 547 U.S. at 584, 126 S.Ct. 2096; Cooey v. Strickland, 604 F.3d 939, 946 (6th Cir.), cert. denied, 559 U.S. 1118, 130 S.Ct. 3272, 176 L.Ed.2d 945 (2010).

The district court's Order dated May 19, 2014, is reversed and the case is remanded for further proceedings not inconsistent with this opinion.

BYE, Circuit Judge, with whom MURPHY and KELLY, Circuit Judges, join, concurring in the result.

I agree the Court's order from May 19, 2014, must be reversed, and I agree this matter should be remanded for further proceedings. However, I cannot agree with the full analysis and commentary of the Court.

First, I disagree with the Court's interpretation of pleading requirements in Eighth Amendment cases. However, even assuming the Court is correct a death row inmate in a facial challenge must identify an alternative method of execution, a death row inmate in an as-applied challenge is not required to do so. Facial and as-applied challenges to execution protocols are different. See Siebert v. Allen, 506 F.3d 1047, 1049-50 (11th Cir.2007) (granting stay on as-applied challenge to execution protocol while denying stay on facial challenge). In stating the pleading standard, the court relies on cases involving facial challenges to the general constitutionality of a particular execution protocol. Those cases did not involve a death penalty inmate arguing his unique medical condition would substantially enhance the likelihood and severity of a painful death. It is my position a death row inmate alleging an Eighth Amendment as-applied challenge need not plead a readily available alternative method of execution. A state cannot be excused from taking into account a particular inmate's existing physical disability or health condition when assessing the propriety of its execution method. When, as here, a death row inmate with a health condition does not have sufficient access to information or testing, that inmate cannot be expected to plead an alternative method.

Second, the Court seems to construe the Supreme Court's denial of stays of execution to eight Zink plaintiffs following In re Lombardi, 741 F.3d 888, 897 reh'g denied, 741 F.3d 903 (8th Cir.), cert. denied Zink v. Lombardi, ___ U.S. ___, 134 S.Ct. 1790, 188 L.Ed.2d 760 (2014), as evidence the Supreme Court agrees with the Eighth Circuit's pleading requirements. However, there is no indication the Supreme Court considered the Eighth Circuit's pleading requirement analysis. Therefore, any such inference from the Supreme Court's recent stay denials is inappropriate.

Third, the Court asserts, without support, the proposition that no physical disability or illness could ever foreclose execution. While the Supreme Court has been clear on the general proposition that, so long as a state-imposed death penalty is constitutional, there must be some way for states to carry out executions, the Supreme Court has also been clear that some individuals cannot be executed. See Hall v. Florida, ___ U.S. ___, 134 S.Ct. 1986, 1992, 188 L.Ed.2d 1007 (2014) ("[P]ersons with intellectual disability may not be executed."); Roper v. Simmons, 543 U.S. 551, 575, 125 S.Ct. 1183, 161 L.Ed.2d 1 (2005) ("[T]he death penalty cannot be imposed upon juvenile offenders ...."); Ford v. Wainwright, 477 U.S. 399, 410, 106 S.Ct. 2595, 91 L.Ed.2d 335 (1986) ("The Eighth Amendment prohibits the State from inflicting the penalty of death upon a prisoner who is insane."). The Supreme Court has not addressed the open question of whether there are some physical disabilities or health conditions which would prevent a state from executing an individual because any execution would be unconstitutionally cruel and unusual based on that individual's particular disability or health condition. This question is not before the Court and the Court's opinion should not be read to answer this question.

Fourth, I do not join in the commentary of Section IV. To begin, the majority asserts, without support from the record, that Bucklew's arguments "raise an inference that he is impermissibly seeking merely to investigate the protocol without taking a position as to what is needed to fix it." It is not the role of this Court to speculate on a party's true intention in filing a lawsuit. Given that a strong possibility of cruel and unusual punishment during Bucklew's death is at stake, the more likely inference from Bucklew's pleadings is that he seeks to remedy those concerns rather than merely satisfy an intellectual curiosity about Missouri's execution protocol or merely delay his execution. And, as noted above, nothing requires Bucklew to propose a specific alternative to the execution protocol; no precedent supports the position that Bucklew is required to "tak[e] a position as to what is needed to fix [the protocol]" in an as-applied challenge.

The Court then restates that Bucklew "at the earliest possible time, [] must identify a feasibly, readily implemented alternative procedure that will significantly reduce a substantial risk of severe pain and that the State refuses to adopt." Bucklew is under no obligation to do so. The Court fails to cite, and I have been unable to find, any support for the proposition Bucklew is required to make any new pleadings, amendments, or motions "at the earliest possible time." It is within the district court's control to set any discovery deadlines and conduct proceedings in the normal order of business. Additionally, for the reasons discussed above, the requirement of providing an alternative execution protocol does not apply in this matter.

Finally, the Court improperly suggests Bucklew's as-applied challenge may not be timely. Such a discussion is unnecessary to the outcome of this appeal, and is improper because the district court has not yet ruled on the issue. Bucklew's prior in camera motion is not before the Court. Additionally, it is for the district court to determine in the first instance whether Bucklew's claim is timely. Despite the Court's suggestion Bucklew's claim may be time-barred, I note Bucklew has put forth substantial evidence to show the claim was brought in a timely manner. This evidence includes: Missouri has changed its protocol many times since imposing a sentence of death on Bucklew; Bucklew's condition has become worse over time; and, because of Missouri's opposition, Bucklew has struggled for years to obtain sufficient scans to fully understand the extent of his health condition. It is for the district court to conclude whether Bucklew improperly delayed in filing his claim.

SHEPHERD, Circuit Judge, with whom MURPHY and BYE, Circuit Judges, join, concurring.

Although I concur in the opinion, I write separately to reiterate my view that a prisoner challenging a method of lethal injection under the Eighth Amendment need not identify an alternative method of execution in the complaint, provided that he concedes other methods of lethal injection would be constitutional. The Court notes that "at the earliest possible time, [Bucklew] must identify a feasible, readily implemented alternative procedure that will significantly reduce a substantial risk of severe pain and that the State refuses to adopt." Consistent with my dissent in Zink, a prisoner must only concede there would be a constitutional method of execution in his complaint and the Court's reference to the "earliest possible time" should not be misconstrued as stating a pleading requirement.