Justice Scalia delivered the opinion of the Court.
The Supreme Court of Kansas vacated the death sentences of Sidney Gleason and brothers Reginald and Jonathan Carr. … We first consider whether the Constitution required the sentencing courts to instruct the juries that mitigating circumstances “need not be proved beyond a reasonable doubt.” And second, whether the Constitution required severance of the Carrs’ joint sentencing proceedings. [In both cases, juries found that the State proved beyond a reasonable doubt the existence of four aggravating circumstances and unanimously agreed to death sentences.]
….
The Kansas Supreme Court vacated the death penalties in both cases. It held that the instructions used in both Gleason’s and the Carrs’ sentencing violated the Eighth Amendment because they “failed to affirmatively inform the jury that mitigating circumstances need only be proved to the satisfaction of the individual juror in that juror’s sentencing decision and not beyond a reasonable doubt.” [Citations to Supreme Court of Kansas opinion omitted throughout.] Without that instruction, according to the court, the jury “was left to speculate as to the correct burden of proof for mitigating circumstances, and reasonable jurors might have believed they could not consider mitigating circumstances not proven beyond a reasonable doubt.” This, the court concluded, might have caused jurors to exclude relevant mitigating evidence from their consideration.
The Kansas Supreme Court also held that the Carrs’ death sentences had to be vacated because of the trial court’s failure to sever their sentencing proceedings, thereby violating the brothers’ Eighth Amendment right “to an individualized capital sentencing determination.” According to the court, [aggravating evidence about each brother tainted the jury’s assessment of the other:] “[T]he defendants’ joint upbringing in the maelstrom that was their family and their influence on and interactions with one another . . . simply was not amenable to orderly separation and analysis.” The Kansas Supreme Court found itself unable to “say that the death verdict was unattributable, at least in part, to this error.” We granted certiorari. 575 U. S. ___ (2015).
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We turn … to the merits of the Kansas Supreme Court’s conclusion that the Eighth Amendment requires capital-sentencing courts in Kansas “to affirmatively inform the jury that mitigating circumstances need not be proven beyond a reasonable doubt.”
Approaching the question in the abstract, and without reference to our capital-sentencing case law, we doubt whether it is even possible to apply a standard of proof to the mitigating-factor determination (the so-called “selection phase” of a capital-sentencing proceeding). It is possible to do so for the aggravating-factor determination (the so-called “eligibility phase”), because that is a purely factual determination. The facts justifying death set forth in the Kansas statute either did or did not exist—and one can require the finding that they did exist to be made beyond a reasonable doubt. Whether mitigation exists, however, is largely a judgment call (or perhaps a value call); what one juror might consider mitigating another might not. And of course the ultimate question whether mitigating circumstances outweigh aggravating circumstances is mostly a question of mercy—the quality of which, as we know, is not strained. … If we were to hold that the Constitution requires the mitigating-factor determination to be divided into its factual component and its judgmental component, and the former to be accorded a burden-of-proof instruction, we doubt whether that would produce anything but jury confusion. In the last analysis, jurors will accord mercy if they deem it appropriate, and withhold mercy if they do not, which is what our case law is designed to achieve.
In any event, our case law does not require capital sentencing courts “to affirmatively inform the jury that mitigating circumstances need not be proved beyond a reasonable doubt.” [Citation omitted.] In Buchanan v. Angelone, 522 U. S. 269 (1998), we upheld a death sentence even though the trial court “failed to provide the jury with express guidance on the concept of mitigation.” Id., at 275. Likewise in Weeks v. Angelone, 528 U. S. 225 (2000), we reaffirmed that the Court has “never held that the State must structure in a particular way the manner in which juries consider mitigating evidence” and rejected the contention that it was constitutionally deficient to instruct jurors to “‘consider a mitigating circumstance if you find there is evidence to support it,’” without additional guidance. Id., at 232–233.
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We reject the Kansas Supreme Court’s decision that jurors were “left to speculate as to the correct burden of proof for mitigating circumstances.” For the reasons we have described, no juror would reasonably have speculated that mitigating circumstances must be proved by any particular standard, let alone beyond a reasonable doubt. The reality is that jurors do not “pars[e] instructions for subtle shades of meaning in the same way that lawyers might.” [Citation omitted.] The instructions repeatedly told the jurors to consider any mitigating factor, meaning any aspect of the defendants’ background or the circumstances of their offense. Jurors would not have misunderstood these instructions to prevent their consideration of constitutionally relevant evidence.
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We turn next to the contention that a joint capital-sentencing proceeding in the Carrs’ cases violated the defendants’ Eighth Amendment right to an “individualized sentencing determination.”
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In light of all the evidence presented at the guilt and penalty phases relevant to the jury’s sentencing determination, the contention that the admission of mitigating evidence by one brother could have “so infected” the jury’s consideration of the other’s sentence as to amount to a denial of due process is beyond the pale. To begin with, the court instructed the jury that it “must give separate consideration to each defendant,” that each was “entitled to have his sentence decided on the evidence and law which is applicable to him,” and that any evidence in the penalty phase “limited to only one defendant should not be considered by you as to the other defendant.” [Record citations omitted throughout.] The court gave defendant-specific instructions for aggravating and mitigating circumstances. And the court instructed the jury to consider the “individual” or “particular defendant” by using four separate verdict forms for each defendant, one for each [victim]. We presume the jury followed these instructions and considered each defendant separately when deciding to impose a sentence of death for each of the brutal murders. [Citation omitted.]
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Joint proceedings are not only permissible but are often preferable when the joined defendants’ criminal conduct arises out of a single chain of events. Joint trial may enable a jury “to arrive more reliably at its conclusions regarding the guilt or innocence of a particular defendant and to assign fairly the respective responsibilities of each defendant in the sentencing.” [Citation omitted.] That the codefendants might have “antagonistic” theories of mitigation, does not suffice to overcome Kansas’s “interest in promoting the reliability and consistency of its judicial process,” [citations omitted]. Limiting instructions, like those used in the Carrs’ sentencing proceeding, “often will suffice to cure any risk of prejudice.” [Citation omitted.] To forbid joinder in capital-sentencing proceedings would, perversely, increase the odds of “wanto[n] and freakis[h]” imposition of death sentences. [Citation omitted.] Better that two defendants who have together committed the same crimes be placed side-by-side to have their fates determined by a single jury.
… The joint sentencing proceedings did not render the sentencing proceedings fundamentally unfair.
* * *
The judgments of the Supreme Court of Kansas are reversed, and these cases are remanded for further proceedings not inconsistent with this opinion.
It is so ordered.
Justice Sotomayor, dissenting.
I respectfully dissent because I do not believe these cases should ever have been reviewed by the Supreme Court. I see no reason to intervene in cases like these— and plenty of reasons not to. Kansas has not violated any federal constitutional right. If anything, the State has overprotected its citizens based on its interpretation of state and federal law. For reasons ably articulated by my predecessors and colleagues and because I worry that cases like these prevent States from serving as necessary laboratories for experimenting with how best to guarantee defendants a fair trial, I would dismiss the writs as improvidently granted.
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The standard adage teaches that hard cases make bad law. [Citation omitted.] I fear that these cases suggest a corollary: Shocking cases make too much law. Because I believe the Court should not have granted certiorari here, I respectfully dissent.
The Supreme Court of Kansas vacated the death sentences of Sidney Gleason and brothers Reginald and Jonathan Carr. … We first consider whether the Constitution required the sentencing courts to instruct the juries that mitigating circumstances “need not be proved beyond a reasonable doubt.” And second, whether the Constitution required severance of the Carrs’ joint sentencing proceedings. [In both cases, juries found that the State proved beyond a reasonable doubt the existence of four aggravating circumstances and unanimously agreed to death sentences.]
….
The Kansas Supreme Court vacated the death penalties in both cases. It held that the instructions used in both Gleason’s and the Carrs’ sentencing violated the Eighth Amendment because they “failed to affirmatively inform the jury that mitigating circumstances need only be proved to the satisfaction of the individual juror in that juror’s sentencing decision and not beyond a reasonable doubt.” [Citations to Supreme Court of Kansas opinion omitted throughout.] Without that instruction, according to the court, the jury “was left to speculate as to the correct burden of proof for mitigating circumstances, and reasonable jurors might have believed they could not consider mitigating circumstances not proven beyond a reasonable doubt.” This, the court concluded, might have caused jurors to exclude relevant mitigating evidence from their consideration.
The Kansas Supreme Court also held that the Carrs’ death sentences had to be vacated because of the trial court’s failure to sever their sentencing proceedings, thereby violating the brothers’ Eighth Amendment right “to an individualized capital sentencing determination.” According to the court, [aggravating evidence about each brother tainted the jury’s assessment of the other:] “[T]he defendants’ joint upbringing in the maelstrom that was their family and their influence on and interactions with one another . . . simply was not amenable to orderly separation and analysis.” The Kansas Supreme Court found itself unable to “say that the death verdict was unattributable, at least in part, to this error.” We granted certiorari. 575 U. S. ___ (2015).
….
We turn … to the merits of the Kansas Supreme Court’s conclusion that the Eighth Amendment requires capital-sentencing courts in Kansas “to affirmatively inform the jury that mitigating circumstances need not be proven beyond a reasonable doubt.”
Approaching the question in the abstract, and without reference to our capital-sentencing case law, we doubt whether it is even possible to apply a standard of proof to the mitigating-factor determination (the so-called “selection phase” of a capital-sentencing proceeding). It is possible to do so for the aggravating-factor determination (the so-called “eligibility phase”), because that is a purely factual determination. The facts justifying death set forth in the Kansas statute either did or did not exist—and one can require the finding that they did exist to be made beyond a reasonable doubt. Whether mitigation exists, however, is largely a judgment call (or perhaps a value call); what one juror might consider mitigating another might not. And of course the ultimate question whether mitigating circumstances outweigh aggravating circumstances is mostly a question of mercy—the quality of which, as we know, is not strained. … If we were to hold that the Constitution requires the mitigating-factor determination to be divided into its factual component and its judgmental component, and the former to be accorded a burden-of-proof instruction, we doubt whether that would produce anything but jury confusion. In the last analysis, jurors will accord mercy if they deem it appropriate, and withhold mercy if they do not, which is what our case law is designed to achieve.
In any event, our case law does not require capital sentencing courts “to affirmatively inform the jury that mitigating circumstances need not be proved beyond a reasonable doubt.” [Citation omitted.] In Buchanan v. Angelone, 522 U. S. 269 (1998), we upheld a death sentence even though the trial court “failed to provide the jury with express guidance on the concept of mitigation.” Id., at 275. Likewise in Weeks v. Angelone, 528 U. S. 225 (2000), we reaffirmed that the Court has “never held that the State must structure in a particular way the manner in which juries consider mitigating evidence” and rejected the contention that it was constitutionally deficient to instruct jurors to “‘consider a mitigating circumstance if you find there is evidence to support it,’” without additional guidance. Id., at 232–233.
….
We reject the Kansas Supreme Court’s decision that jurors were “left to speculate as to the correct burden of proof for mitigating circumstances.” For the reasons we have described, no juror would reasonably have speculated that mitigating circumstances must be proved by any particular standard, let alone beyond a reasonable doubt. The reality is that jurors do not “pars[e] instructions for subtle shades of meaning in the same way that lawyers might.” [Citation omitted.] The instructions repeatedly told the jurors to consider any mitigating factor, meaning any aspect of the defendants’ background or the circumstances of their offense. Jurors would not have misunderstood these instructions to prevent their consideration of constitutionally relevant evidence.
….
We turn next to the contention that a joint capital-sentencing proceeding in the Carrs’ cases violated the defendants’ Eighth Amendment right to an “individualized sentencing determination.”
….
In light of all the evidence presented at the guilt and penalty phases relevant to the jury’s sentencing determination, the contention that the admission of mitigating evidence by one brother could have “so infected” the jury’s consideration of the other’s sentence as to amount to a denial of due process is beyond the pale. To begin with, the court instructed the jury that it “must give separate consideration to each defendant,” that each was “entitled to have his sentence decided on the evidence and law which is applicable to him,” and that any evidence in the penalty phase “limited to only one defendant should not be considered by you as to the other defendant.” [Record citations omitted throughout.] The court gave defendant-specific instructions for aggravating and mitigating circumstances. And the court instructed the jury to consider the “individual” or “particular defendant” by using four separate verdict forms for each defendant, one for each [victim]. We presume the jury followed these instructions and considered each defendant separately when deciding to impose a sentence of death for each of the brutal murders. [Citation omitted.]
….
Joint proceedings are not only permissible but are often preferable when the joined defendants’ criminal conduct arises out of a single chain of events. Joint trial may enable a jury “to arrive more reliably at its conclusions regarding the guilt or innocence of a particular defendant and to assign fairly the respective responsibilities of each defendant in the sentencing.” [Citation omitted.] That the codefendants might have “antagonistic” theories of mitigation, does not suffice to overcome Kansas’s “interest in promoting the reliability and consistency of its judicial process,” [citations omitted]. Limiting instructions, like those used in the Carrs’ sentencing proceeding, “often will suffice to cure any risk of prejudice.” [Citation omitted.] To forbid joinder in capital-sentencing proceedings would, perversely, increase the odds of “wanto[n] and freakis[h]” imposition of death sentences. [Citation omitted.] Better that two defendants who have together committed the same crimes be placed side-by-side to have their fates determined by a single jury.
… The joint sentencing proceedings did not render the sentencing proceedings fundamentally unfair.
* * *
The judgments of the Supreme Court of Kansas are reversed, and these cases are remanded for further proceedings not inconsistent with this opinion.
It is so ordered.
Justice Sotomayor, dissenting.
I respectfully dissent because I do not believe these cases should ever have been reviewed by the Supreme Court. I see no reason to intervene in cases like these— and plenty of reasons not to. Kansas has not violated any federal constitutional right. If anything, the State has overprotected its citizens based on its interpretation of state and federal law. For reasons ably articulated by my predecessors and colleagues and because I worry that cases like these prevent States from serving as necessary laboratories for experimenting with how best to guarantee defendants a fair trial, I would dismiss the writs as improvidently granted.
….
The standard adage teaches that hard cases make bad law. [Citation omitted.] I fear that these cases suggest a corollary: Shocking cases make too much law. Because I believe the Court should not have granted certiorari here, I respectfully dissent.