In the Court’s recent decision in United States v. Tsarnaev, Justice Thomas appears to be planting the seeds for overturning longstanding precedent in death penalty trial procedure. A line of cases on capital mitigation—evidence in favor of sparing the life of a criminal defendant facing the death penalty—has both expanded the scope of mitigating evidence and afforded wide latitude to sentencing decision-makers when evaluating this evidence. The Essay asserts that in opposing this line of cases, Justice Thomas improperly ignores the procedural safeguard function that mitigation’s deliberative liberties serve at a capital trial. This safeguard function is indispensable: even with it in place, the existing system has produced convictions and death sentences of innocent individuals, some of whom have likely been executed. The Essay casts a much-needed spotlight on the logic of mitigation as procedural safeguard, arguing that any attempt to overturn precedent must explain why this logic and its aspiration to heightened reliability no longer apply when it comes to the nation’s ultimate punishment.
In 2022, the U.S. Supreme Court took up the case of Dzhokhar Tsarnaev, sentenced to death for his role in the Boston Marathon bombings.1 At his original trial, Mr. Tsarnaev had sought to introduce evidence that his acts came under the coercive influence of his brother, Tamerlan. The defense wished to present an FBI affidavit in which an associate of Tamerlan described the latter’s vicious, threatening behavior leading up to the throat-slitting murders of three men years earlier, carried out by Tamerlan himself. Under a longstanding principle of capital trial procedure, sentencing decision-makers (whether jurors or judges) have the prerogative to consider a wide range of mitigating evidence in favor of sparing the defendant’s life. This includes facts concerning the circumstances of the capital offense. Tamerlan’s history of domineering violence, the defense argued, would provide crucial context to explain his little brother’s involvement in the bombings. But in the majority opinion, Justice Thomas affirmed the inadmissibility of this evidence, essentially on the argument that the trial court was to be afforded strong deference on review.2
U.S. v. Tsarnaev has the nation’s capital defense bar worried.3 The ruling pushes back on a line of cases, going back half a century, that have clarified the deliberative liberties associated with capital mitigation—the expansive scope of mitigating evidence that sentencers may consider—as well as the wide latitude enjoyed by sentencers when evaluating that evidence. What’s more, a footnote in the majority opinion wonders aloud whether that line of cases even falls under the proper scope of the Eighth Amendment.4 Given the current Court’s willingness to revisit precedent, defense advocates are suspecting that Justice Thomas has his eye on an overhaul of long-established capital sentencing procedures.
Should it ever come to pass, a future ruling by Justice Thomas will surely take its cue from the late Justice Scalia. In a dissent in Walton v. Arizona,5 Justice Scalia criticized the Supreme Court’s line of mitigation cases as the judicial regulation of process gone askew. In his view—as later embraced by Justice Thomas—to allow sentencers unbridled consideration of expansive mitigating evidence would be to risk undue arbitrariness in death verdicts.6 Such arbitrariness was the very concern that, in 1972, had compelled the landmark case of Furman v. Georgia7 to temporarily put the brakes on all capital sentencing in the nation.8 For Justices Scalia and Thomas, the mitigation cases can’t be squared with the need to “channel[] and limit[] . . . the sentencer’s discretion”9 in order to achieve a more principled and predictable death penalty.
In this Essay, I contend that this position improperly ignores the fundamental logic behind mitigation’s deliberative liberties. These liberties serve as the ultimate procedural safeguard at trial against undue impositions of the ultimate criminal punishment.10 Mitigation produces individualized, morally driven sentencing outcomes that are intended to err on the side of life, with the goal of ensuring the heightened reliability of death sentences. Consequently, when mitigation’s liberties allow decision-makers to pass sentences in favorem vitae, such outcomes are never “arbitrary,” but a product of intentional design. It’s on the other side of the equation—the specific procedural requirements that dictate the considerations calling for death—where assessments of arbitrariness correctly kick in, requiring clear guidance that channels and limits sentencers’ decisions to impose the death penalty.
Under the current regime of capital punishment, defendants have been convicted and sentenced to death for crimes they didn’t commit.11 Very likely, some of these individuals have been executed12—and this is a system in which mitigation is still operating. This is not a context in which the judiciary should be planning how to scrap procedural safeguards against undue sentences of death. Against this backdrop, the Essay casts a much-needed spotlight on the logic of mitigation as procedural safeguard. In so doing, I argue that any attempt to overturn precedent must do the heavy lifting of explaining why mitigation as procedural safeguard, with its aspiration to heightened reliability, is now no longer a constitutional necessity for the country’s most extreme punishment.
I. The Woodson-Lockett Line of Cases
Justice Scalia’s stance on mitigating evidence was unmistakably clear: it has no place in capital trials. In Walton v. Arizona, his dissent endorsed a so-called “mandatory sentencing” scheme that would automatically impose death upon conviction of certain crimes.13 Nearly two decades earlier, however, mandatory sentencing statutes had already been prohibited in a group of Supreme Court cases that brought the death penalty back into play after Furman.14 Justice Stewart, writing for a plurality in Woodson v. North Carolina,15 stated that such schemes prevent sentencers from considering “compassionate or mitigating factors stemming from the diverse frailties of humankind.”16 Mandatory sentencing treats capital defendants “not as uniquely individual human beings, but as members of a faceless, undifferentiated mass . . . .”17 Crucially, Justice Stewart associated individualizing mitigating evidence with “the need for reliability”18 in administering a sentence so final in its consequences.
Woodson was the first in the line of cases expanding the sentencer’s ability to evaluate broad-reaching mitigation. Two years later, Lockett v. Ohio19 became the second. Ohio’s capital statute had limited mitigating evidence to specific enumerated factors, preventing assessment of the defendant’s lack of intent to cause the victim’s death and the defendant’s minor role in the offense compared with her co-defendants.20 The Court held that sentencers must “not be precluded from considering, as a mitigating factor, any aspect of a defendant’s character or record and any of the circumstances of the offense that the defendant proffers as a basis for a sentence less than death.”21 In stating this principle, the opinion once again emphasized the “greater degree of reliability”22 that must attend a criminal punishment different from any other.
The reasoning of Woodson and Lockett—both plurality opinions—was embraced in subsequent majority rulings.23 The Court proceeded to validate the scope of mitigating evidence to span the defendant’s childhood and adult years, covering the adversity of their life circumstances and their potential for redemption,24 as well as their behavior in confinement after the capital offense.25 Furthermore, the Court clarified the sentencer’s liberties when deliberating how mitigating evidence figures in the sentencing verdict. Statutes can’t constrain decision-makers as to what weight or meaning to imbue any given piece of evidence.26 And each sentencer has the prerogative to make their own personal decision about what evidence they accept to be factually true and mitigating in nature.27 This is a vital point given that in most jurisdictions, even one juror holdout can prevent a verdict of death.28
Justice Scalia’s dissent in Walton lambasted what he called the “Woodson-Lockett line of cases.”29 The key takeaway from Furman, he wrote, was that capital statutes must articulate “‘clear and objective standards’ that provide ‘specific and detailed guidance’”30 in order to minimize arbitrary decision-making. For Justice Scalia, the expansion of mitigation to include any evidence bearing on the defendant’s lifetime existence writ large, along with sentencers’ leeway in evaluating that evidence, flat out squashed any aspiration to “guided discretion”31 in death sentencing. As he put it, “the practice which in Furman had been described as the discretion to sentence to death and pronounced constitutionally prohibited was in Woodson and Lockett renamed the discretion not to sentence to death and pronounced constitutionally required.”32
Justice Scalia declared the tension between Furman and the Woodson-Lockett line of cases to be irreconcilable. Consequently, he announced, no longer would he enforce the latter as long as he remained on the bench.33 He held true to his word.
II. Mitigation as Procedural Safeguard
The flaw in Justice Scalia’s position is betrayed in another dissent he authored. He there stated, “The decision whether to impose the death penalty is a unitary one; unguided discretion not to impose is unguided discretion to impose as well.”34 But the deliberative requirements that militate in favor of death are not equivalent to the requirements that permit sentencers to decide against it. For the former, there must be built-in constraints in the manner Justice Scalia had correctly stated: sentencing discretion is to be channeled and limited by clear and objective standards providing specific and detailed guidance.35 In contrast, however, the latter allows liberties for capital sentencers that are justified by the core function of mitigation: to serve as a procedural safeguard in preventing unwarranted sentences of death.36 Mitigation aims to ensure heightened reliability in sentencing trial outcomes that do result in death. And the way it does so is by permitting sentencers to err on the side of life.
It was Justice Stewart, again, who kicked off the Woodson-Lockett line of cases. But in fact, the logic of mitigation as procedural safeguard may have figured even earlier for him. In one of the cases that reinstated capital punishment after Furman, Justice Stewart wrote for the majority in upholding a Georgia statute in which jurors could impose death only upon finding specific aggravating factors—for example, the commission of the crime for pecuniary gain, or the defendant’s prior convictions for capital offenses.37 Notably, the statute specifically enumerated ten aggravating factors . . . and exactly zero mitigating ones.38 Specific and detailed guidance was required only of the factors that operate in favor of death. Sentencers had much wider discretion to consider the breadth of evidence they deemed to work against it.
This becomes even more interesting in light of Justice Stewart’s response to one of the arguments the petitioner put forth to strike down Georgia’s statute. Georgia explicitly allowed jurors to reject a death sentence even in the complete absence of any mitigating circumstances.39 In the presence of proven aggravating factors, the petitioner averred, it was unconstitutionally arbitrary for Georgia to allow jurors baseless discretion to reject the death penalty.40 This was exactly what Justice Scalia had feared: capricious verdicts for life. But to this argument, Justice Stewart replied, “[T]he isolated decision of a jury to afford mercy does not render unconstitutional death sentences imposed on defendants who were sentenced under a system that does not create a substantial risk of arbitrariness or caprice.”41
Contrary to Justice Scalia’s claim, then, capital deliberations are not unitary. They proceed on dual tracks. Under the logic of mitigation as procedural safeguard, the focus of regulation lies primarily on channeling the considerations that lead to verdicts for death (“guided discretion”). A decade after Justice Stewart’s ruling, the Court appeared to confirm as much outright: “In contrast to the carefully defined standards that must narrow a sentencer’s discretion to impose the death sentence, the Constitution limits a State’s ability to narrow a sentencer’s discretion to consider relevant evidence that might cause it to decline to impose the death sentence.”42
In theory, ours is a system that would rather ten guilty individuals go free than one innocent individual be convicted. From this perspective—with the preservation of not liberty, but life at stake in capital cases—the logic of mitigation’s procedural safeguard function comes into clear view. For those who appreciate the power of the sovereign state in administering the most irreversible of punishments, it makes sense for capital sentencing procedure to ensure that sentencers, before passing ultimate judgment on a human life, have the fullest information possible about that human life and the fullest discretion possible when assessing that information. By this design, to equate the discretion to err on the side of life with the discretion to sentence to death is to equate apples with oranges.
As a matter of fact, existing deliberative requirements in favor of death could very well be falling short of the “guided discretion” that Furman requires. Scholars have suggested, for instance, that highly subjective aggravating factors that contemplate the “especially heinous, atrocious, or cruel” nature of the murder are unpredictable in application.43 One might immediately think of the specter of race. Other commentators have noted the phenomenon of “aggravator creep,” whereby capital statutes add more and more aggravating factors to the point that the class of death-eligible defendants ends up being not meaningfully narrowed to the purported worst of the worst.44 In this regard, to locate mitigation as the wellspring of unconstitutional arbitrariness is, quite literally, to misplace the criticism.
And yet, even as the Supreme Court has refrained from meaningfully channeling deliberative processes on the pro-death track,45 it has quietly chipped away at sentencers’ deliberative liberties on the anti-death one. The Court has held it proper to instruct jurors that they mustn’t be swayed by “mere sentiment”46 without any evidentiary basis. A subsequent decision affirmed a jury instruction directing that sentencers “shall impose”47 life or death based on how aggravating and mitigating evidence stack up against one another. Both these cases deemed it permissible to limit the sentencer’s prerogative to withhold death for any reason.48 The Court has also ruled that a jury’s residual doubt about the defendant’s guilt49 is not a proper mitigating factor, because residual doubt is not pertinent to the defendant’s character or record, or the circumstances of the offense50—a decision with particularly grim implications given the death sentencing (and probable execution) of innocent individuals. The Court’s recent decision in Tsarnaev, then, continues a longstanding trend of small but significant moves to weaken mitigation’s safeguard function.
This takes us back, finally, to Justice Thomas himself. Two years after his appointment to the Court, he revealed his views on capital sentencing procedure in a concurring opinion in Graham v. Collins.51 Like Justice Scalia, he endorses mandatory sentencing schemes that would do away with mitigation wholesale.52 And like Justice Scalia, he believes that the expansion of mitigation’s liberties has sabotaged the quest for guided discretion. His opinion in Graham took issue with a prior Supreme Court ruling that had overturned Texas’s capital statute for improperly preventing sentencers from considering the full range of mitigating evidence, contra the Woodson-Lockett cases.53 Quoting none other than Justice Scalia, Justice Thomas criticized that ruling for affirming “‘a scheme that simply dumps before the jury all sympathetic factors bearing upon the defendant’s background and character, and the circumstances of the offense, so that the jury may decide without further guidance’ whether the defendant deserves death.”54
Where Justice Thomas ventured out on his own was with his thoughts on race. In Graham, he observed that “Furman v. Georgia was decided in an atmosphere suffused with concern about race bias in the administration of the death penalty . . . .”55 Race, he noted, was an explicit consideration in three opinions in Furman separately authored by justices who ruled with the majority.56 And these opinions, he pointed out, drew from rhetoric and empirical support provided by the NAACP lawyers who’d argued for the petitioners, all of them Black. Justice Thomas asserted that the unbridled discretion unleashed by Woodson-Locket allows racial bias—“the paradigmatic capricious and irrational sentencing factor”—to skew sentencing outcomes in ways that arbitrarily favor some while disfavoring others.57 He wrote, “To withhold the death penalty out of sympathy for a defendant who is a member of a favored group is no different from a decision to impose the penalty on the basis of negative bias . . . .”58
This analysis charted new ground—and yet, Justice Thomas’s mistake was identical to Justice Scalia’s before him. He failed to acknowledge mitigation’s function as procedural safeguard. Once this function is recognized, it immediately becomes obvious that the manner in which a safeguard is applied is a different question from the legitimacy of that safeguard itself. The Fourth Amendment right against unreasonable search and seizure, for example, is a quintessential safeguard of constitutional criminal procedure. It’s long been well-known that police have applied Fourth Amendment protections in arbitrary, racially discriminatory ways.59 But inequitable application alone doesn’t require that the Fourth Amendment be stricken from American criminal procedure any more than it requires that mitigation be stricken from capital trial procedure.
In Justice Thomas’s conflation of the safeguard with its application, the criticism is once again misplaced. Mitigation is not the cause of racism. Racism is the cause of racism. In any future hypothetical ruling by Justice Thomas, ostensible concern for racial fairness shouldn’t obfuscate the real role of mitigation’s deliberative liberties in seeking heightened reliability, safeguarding against unwarranted impositions of death.
This Essay has bracketed for another day the question raised in Justice Thomas’s footnote in Tsarnaev—whether the Woodson-Lockett line of cases properly falls under the Eighth Amendment’s scope. I’d point out that a future Justice Thomas opinion will almost certainly draw yet again from Justice Scalia, whose dissent in Walton framed the issue exactly as Justice Thomas’s footnote did.60
Regardless of how he makes the argument, however, the fact stands that Justice Thomas’s substantive arguments against the Woodson-Lockett line of cases fails to address the concerns and values that have established its deliberative liberties in stare decisis. This is particularly concerning in a time when growing public misgivings about capital punishment are centered on the fairness of its administration.61 The question of life or death is the most momentous decision a criminal sentencer can make. According to the logic of mitigation as procedural safeguard, the most appropriate way to prevent undue deprivations of human life at trial is to provide the decision-maker with the fullest range of liberties to deliberate on the fullest range of evidence about the specific human life that’s on the line.
* Assistant Professor, DePaul University College of Law. Special thanks to Sean O’Brien. All errors are my own.
1. See generally United States v. Tsarnaev, 595 U.S. 302 ((2022).
2. Id. at 323.
3. Joe Sexton, Could People Facing the Death Penalty Lose the Right to Tell Juries Their Life Stories?, The Marshall Project (Sept. 17, 2024), https://themarshallproject.org/2024/09/17/supreme-court-death-penalty-jury-overturn-precedent [https://perma.cc/H3R6-AUGS].
4. See Tsarnaev, 595 U.S. at 318 n.2 (“Some have argued that these cases and their progeny do not reflect the original meaning of the Eighth Amendment, whose prohibition ‘relates to the character of the punishment, and not the process by which it is imposed.’” (citation omitted)).
5. Walton v. Arizona, 497 U.S. 639, 656–74 (1990) (Scalia, J., dissenting).
6. Id.
7. 408 U.S. 238 (1972).
8. See id. at 309 (Stewart, J., concurring) (noting that petitioners’ death sentences “are cruel and unusual in the same way that being struck by lightning is cruel and unusual”).
9. Walton, 497 U.S. at 660 (Scalia, J., dissenting) (citation omitted).
10. There are, of course, other procedural safeguards on appeal and postconviction.
11. Samuel R. Gross et al., Rate of False Conviction of Criminal Defendants Who Are Sentenced to Death, 111 PNAS 7230 (2014) (estimating that 4.1% of individuals sentenced to death are innocent); Innocence and the Death Penalty, Innocence Project, https://innocenceproject.org/innocence-and-the-death-penalty/ (last visited Apr. 15, 2025) [https://perma.cc/5PQ2-HPA3] (noting that at least 200 people who were wrongly convicted and sentenced to death have been exonerated since 1973).
12. Executed but Possibly Innocent, Death Penalty Info. Ctr., https://deathpenaltyinfo.org/policy-issues/innocence/executed-but-possibly-innocent (last visited Apr. 15, 2025) [https://perma.cc/3EHS-8U3R] (providing details of twenty such cases).
13. Walton, 497 U.S. at 671 (Scalia, J., dissenting).
14. Gregg v. Georgia, 428 U.S. 153 (1976); Proffitt v. Florida, 428 U.S. 242 (1976); Jurek v. Texas, 428 U.S. 262 (1976); Woodson v. North Carolina, 428 U.S. 280 (1976); Roberts v. Louisiana, 431 U.S. 633 (1977).
15. See generally 428 U.S. 280 (plurality opinion).
16. Id. at 304.
17. Id. at 303.
18. Id.
19. See generally 438 U.S. 586 (1978) (plurality opinion).
20. Id. at 597.
21. Id. at 604 (footnote omitted).
22. Id.
23. See Sumner v. Shuman, 483 U.S. 66 (1987) (adopting Woodson); Eddings v. Oklahoma, 455 U.S. 104 (1982) (adopting Lockett).
24. Hitchcock v. Dugger, 481 U.S. 393, 395–96 (1987).
25. See Skipper v. South Carolina, 476 U.S. 1, 10 (1986) (Powell, J., concurring).
26. See Penry v. Lynaugh, 492 U.S. 302, 354–55 (1989) (Scalia, J., concurring).
27. McKoy v. North Carolina, 494 U.S. 433, 433 (1990).
28. When Jurors Do Not Agree, Should a Death Sentence Be Imposed?, Death Penalty Info. Ctr. (Sept. 13, 2023), https://deathpenaltyinfo.org/when-jurors-do-not-agree-should-a-death-sentence-be-imposed [https://perma.cc/B8LW-JP84].
29. Walton v. Arizona, 497 U.S. 639, 671 (1990) (Scalia, J., dissenting) (citation omitted).
30. Id. (citation omitted).
31. Id. at 661.
32. Id. at 663.
33. Id. at 673.
34. Penry v. Lynaugh, 492 U.S. 302, 360 (1989) (Scalia, J., dissenting).
35. See id.
36. See id.
37. Gregg v. Georgia, 428 U.S. 153, 197–98 (1976).
38. See Ga. Code Ann. § 27-2534.1 (Supp. 1975) (superseded).
39. Gregg, 428 U.S. at 197.
40. Id. at 197–98.
41. Id. at 203.
42. McCleskey v. Kemp, 481 U.S. 279, 304 (1987) (footnote omitted).
43. See Richard A. Rosen, The “Especially Heinous” Aggravating Circumstance in Capital Cases—The Standardless Standard, 64 N.C. L. Rev. 941 (1986) (analyzing state appellate decisions to reveal sentencers’ inconsistent application of this aggravator); Jeffrey L. Kirchmeier, Aggravating and Mitigating Factors: The Paradox of Today’s Arbitrary and Mandatory Capital Punishment Scheme, 6 Wm. & Mary Bill Rts. J. 345, 363–68 (1998) (noting courts’ reluctance to strike this aggravator on grounds of overbreadth or vagueness).
44. See Symposium: Toward a Model Death Penalty Code: The Massachusetts Governor’s Council Report. Panel One—The Capital Crime, 80 Ind. L. J. 35, 35 (2005).
45. See Carol S. Steiker & Jordan M. Steiker, Aggravating and Mitigating Evidence, in Routledge Handbook on Capital Punishment 279, 284 (Robert M. Bohm & Gavin Lee eds., 2018) (summarizing the Supreme Court’s capital sentencing decisions as “diminish[ing] the significance and functionality of aggravating factors as a tool to constrain capital sentencing discretion”).
46. California v. Brown, 479 U.S. 538, 642 (1987).
47. Boyde v. California, 494 U.S. 370, 374 (1987).
48. See Brown, 497 U.S. at 642; see also Boyde, 494 U.S. at 374.
49. The doubt is “residual” because the same jury that decides the question of the defendant’s guilt is typically the same jury that decides the question of that defendant’s sentence.
50. Franklin v. Lynaugh, 487 U.S. 164, 173–75 (1988).
51. Graham v. Collins, 506 U.S. 461, 478–500 (1993) (Thomas, J., concurring).
52. Id. at 487.
53. See Penry v. Lynaugh, 492 U.S. 302, 315–16 (1989).
54. Graham, 506 U.S. at 493 (Thomas, J., concurring) (citation omitted).
55. Id. at 479.
56. Id. at 479–80.
57. Id. at 484.
58. Id. at 495.
59. See, e.g., Devon W. Carbado, From Stopping Black People to Killing Black People: The Fourth Amendment Pathways to Police Violence, 105 Cal. L. Rev. 125, 132–40 (2017) (discussing the lethal consequences of racial profiling under the Fourth Amendment); Tracey Maclin, Race and the Fourth Amendment, 51 Vand. L. Rev. 333, 344–54 (1998) (summarizing empirical evidence demonstrating the unfounded use of race in traffic stops).
60. Walton v. Arizona, 497 U.S. 639, 670 (1990) (Scalia, J., dissenting) (stating that the Eighth Amendment “does not, by its terms, regulate the procedures of sentencing as opposed to the substance of punishment”).
61. Megan Brenan, New 47% Low Say Death Penalty Is Fairly Applied in U.S., Gallup (Nov. 6, 2023), https://news.gallup.com/poll/513806/new-low-say-death-penalty-fairly-applied.aspx [https://perma.cc/8RXN-SEVL].
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