Boyde v. California/Opinion of the Court
This case requires us to decide whether two California jury instructions used in the penalty phase of petitioner's capital murder trial and in other California capital cases before each was modified in 1983 and 1985, respectively, are consistent with the requirements of the Eighth Amendment. We hold that they are.
Petitioner Richard Boyde was found guilty by a jury in the robbery, kidnaping, and murder of Dickie Gibson, the night clerk at a 7-Eleven Store in Riverside, California. The State introduced evidence at trial that about 2:30 a.m. on January 15, 1981, Boyde entered the store and robbed the clerk at gunpoint of $33 from the cash register. Petitioner then forced Gibson into a waiting car, which was driven by petitioner's nephew, and the three men drove to a nearby orange grove. There, Boyde brought Gibson into the grove and ordered him to kneel down with his hands behind his head. As Gibson begged for his life, Boyde shot him once in the back of the head and again in the forehead, killing him. The jury returned a special verdict that Boyde personally committed the homicide with "express malice aforethought and premeditation and deliberation."
At the penalty phase of the trial, the jury was instructed, inter alia, in accordance with instructions 8.84.1 and 8.84.2, 1 California Jury Instructions, Criminal (4th ed. 1979) (CALJIC), both of which have since been amended. The former lists 11 factors that the jury "shall consider, take into account and be guided by" in determining whether to impose a sentence of death or life imprisonment.  The eleventh is a "catch-all," factor (k), which reads: "Any other circumstance which extenuates the gravity of the crime even though it is not a legal excuse for the crime."  The court's concluding instruction, pursuant to CALJIC 8.84.2, again told the jury to consider all applicable aggravating and mitigating circumstances and followed with this direction: "If you conclude that the aggravating circumstances outweigh the mitigating circumstances, you shall impose a sentence of death. However, if you determine that the mitigating circumstances outweigh the aggravating circumstances, you shall impose a sentence of confinement in the state prison for life without the possibility of parole." (Emphasis added.)  After hearing six days of testimony concerning the appropriate penalty, the jury returned a verdict imposing the sentence of death, and the trial court denied Boyde's motion to reduce the sentence.
On appeal, the Supreme Court of California affirmed. 46 Cal.3d 212, 250 Cal.Rptr. 83, 758 P.2d 25 (1988). It rejected petitioner's contention that the jury instructions violated the Eighth Amendment because the so-called "unadorned version" of factor (k) did not allow the jury to consider mitigating evidence of his background and character. The court noted that all of the defense evidence at the penalty phase related to Boyde's background and character, that the jury was instructed to consider " 'all of the evidence which has been received during any part of the trial of this case,' " and that the prosecutor "never suggested that the background and character evidence could not be considered." Id., at 251, 250 Cal.Rptr., at 105, 758 P.2d, at 47. Therefore, the court found it "inconceivable the jury would have believed that, though it was permitted to hear defendant's background and character evidence and his attorney's lengthy argument concerning that evidence, it could not consider that evidence." Ibid.
With regard to the "shall impose" language of CALJIC 8.84.2, the court agreed with petitioner that the instruction could not permissibly require a juror to vote for the death penalty " 'unless, upon completion of the "weighing" process, he decides that death is the appropriate penalty under all the circumstances.' " 46 Cal.3d, at 253, 250 Cal.Rptr., at 106, 758 P.2d, at 48 (quoting People v. Brown, 40 Cal.3d 512, 541, 230 Cal.Rptr. 834, 849, 726 P.2d 516, 532 (1985)). It concluded, however, that in this case "[t]he jury was adequately informed as to its discretion in determining whether death was the appropriate penalty." 46 Cal.3d, at 253, 250 Cal.Rptr., at 106, 758 P.2d, at 48. Three justices dissented from the court's affirmance of the death sentence. The dissenters argued that the mandatory feature of instruction 8.84.2 misled the jury into believing that it was required to impose the death penalty if the aggravating factors "outweighed" the mitigating factors, even though an individual juror might not have thought death was the appropriate penalty in this case. Id., at 257-266, 250 Cal.Rptr., at 109-115, 758 P.2d, at 51-57. We granted certiorari, 490 U.S. 1097, 109 S.Ct. 2447, 104 L.Ed.2d 1002 (1989), and now affirm.
Petitioner reiterates in this Court his argument that the mandatory nature of former CALJIC 8.84.2 resulted in a sentencing proceeding that violated the Eighth Amendment, because the instruction prevented the jury from making an "individualized assessment of the appropriateness of the death penalty." See Penry v. Lynaugh, 492 U.S. 302, 319, 109 S.Ct. 2934, 2947, 106 L.Ed.2d 256 (1989). Specifically, Boyde contends that the "shall impose" language of the jury instruction precluded the jury from evaluating the "absolute weight" of the aggravating circumstances and determining whether they justified the death penalty. He further asserts that the jury was prevented from deciding whether, in light of all the aggravating and mitigating evidence, death was the appropriate penalty. In response, the State argues that the sentencing proceeding was consistent with the Eighth Amendment, because a reasonable juror would interpret the instruction as allowing for the exercise of discretion and moral judgment about the appropriate penalty in the process of weighing the aggravating and mitigating circumstances.
We need not discuss petitioner's claim at length, because we conclude that it is foreclosed by our decision earlier this Term in Blystone v. Pennsylvania, 494 U.S. 299, 110 S.Ct. 1078, 108 L.Ed.2d 255 (1990). In Blystone, we rejected a challenge to an instruction with similar mandatory language, holding that "[t]he requirement of individualized sentencing in capital cases is satisfied by allowing the jury to consider all relevant mitigating evidence." Id., at 307, 110 S.Ct., at 1083. Although Blystone, unlike Boyde, did not present any mitigating evidence at the penalty phase of his capital trial, the legal principle we expounded in Blystone clearly requires rejection of Boyde's claim as well, because the mandatory language of CALJIC 8.84.2 is not alleged to have interfered with the consideration of mitigating evidence. Petitioner suggests that the jury must have freedom to decline to impose the death penalty even if the jury decides that the aggravating circumstances "outweigh" the mitigating circumstances. But there is no such constitutional requirement of unfettered sentencing discretion in the jury, and States are free to structure and shape consideration of mitigating evidence "in an effort to achieve a more rational and equitable administration of the death penalty." Franklin v. Lynaugh, 487 U.S. 164, 181, 108 S.Ct. 2320, 2331, 101 L.Ed.2d 155 (1988) (plurality opinion). Petitioner's claim that the "shall impose" language of CALJIC 8.84.2 unconstitutionally prevents "individualized assessment" by the jury is thus without merit.
The second issue in this case is whether petitioner's capital sentencing proceedings violated the Eighth Amendment because the trial court instructed the jury in accordance with former CALJIC 8.84.1, including the "unadorned" factor (k). The Eighth Amendment requires that the jury be able to consider and give effect to all relevant mitigating evidence offered by petitioner. See Lockett v. Ohio, 438 U.S. 586, 98 S.Ct. 2954, 57 L.Ed.2d 973 (1978); Eddings v. Oklahoma, 455 U.S. 104, 102 S.Ct. 869, 71 L.Ed.2d 1 (1982); Penry, supra. In assessing the effect of a challenged jury instruction, we follow the familiar rule stated in Cupp v. Naughten, 414 U.S. 141, 94 S.Ct. 396, 38 L.Ed.2d 368 (1973):
"In determining the effect of this instruction on the validity of respondent's conviction, we accept at the outset the well-established proposition that a single instruction to a jury may not be judged in artificial isolation, but must be viewed in the context of the overall charge. Boyd v. United States, 271 U.S. 104, 107 [46 S.Ct. 442, 443, 70 L.Ed. 857] (1926)." Id., at 146-147, 94 S.Ct., at 400.
Petitioner contends that none of the 11 statutory factors in CALJIC 8.84.1 allowed the jury to consider non-crime-related factors, such as his background and character, which might provide a basis for a sentence less than death. Nine of the factors, he argues, focused only on the immediate circumstances of the crime itself. Two others, factors (b) and (c), which center on the presence or absence of prior violent criminal activity and prior felony convictions, were in petitioner's view simply vehicles for the consideration of aggravating evidence not directly related to the crime. Finally, petitioner claims that the "catch-all" factor (k) did not allow the jury to consider and give effect to non-crime-related mitigating evidence, because its language-"[a]ny other circumstance which extenuates the gravity of the crime" limited the jury to other evidence that was related to the crime.
The legal standard for reviewing jury instructions claimed to restrict impermissibly a jury's consideration of relevant evidence is less than clear from our cases. In Francis v. Franklin, 471 U.S. 307, 105 S.Ct. 1965, 85 L.Ed.2d 344 (1985), we said that "[t]he question . . . is . . . what a reasonable juror could have understood the charge as meaning." Id., at 315-316, 105 S.Ct., at 1972 (emphasis added). See also Sandstrom v. Montana, 442 U.S. 510, 516-517, 99 S.Ct. 2450, 2455-2466, 61 L.Ed.2d 39 (1979). But our subsequent decisions, while sometimes purporting to apply the Francis standard, have not adhered strictly to that formulation. In California v. Brown, 479 U.S. 538, 541-542, 107 S.Ct. 837, 839-840, 93 L.Ed.2d 934 (1987), we made reference both to what a reasonable juror "could " have done and what he "would " have done. And two Terms ago in Mills v. Maryland, 486 U.S. 367, 108 S.Ct. 1860, 100 L.Ed.2d 384 (1988), we alluded to at least three different inquiries for evaluating such a challenge: whether reasonable jurors "could have " drawn an impermissible interpretation from the trial court's instructions, id., at 375-376, 108 S.Ct., at 1866 (emphasis added); whether there is a "substantial possibility that the jury may have rested its verdict on the 'improper' ground," id., at 377, 108 S.Ct., at 1867 (emphasis added); and how reasonable jurors "would have " applied and understood the instructions. Id., at 389, 108 S.Ct., at 1872 (WHITE, J., concurring) (emphasis added). Other opinions in the area likewise have produced a variety of tests and standards. See, e.g., Penry v. Lynaugh, 492 U.S., at 326, 109 S.Ct., at 2951 ("[A] reasonable juror could well have believed that there was no vehicle for expressing the view that Penry did not deserve to be sentenced to death based upon his mitigating evidence") (emphasis added); Franklin v. Lynaugh, supra, 487 U.S., at 192, 108 S.Ct., at 2337 (STEVENS, J., dissenting) ("[N]either of the Special Issues as they would have been understood by reasonable jurors gave the jury the opportunity to consider petitioner's mitigating evidence") (emphasis added); see also Andres v. United States, 333 U.S. 740, 752, 68 S.Ct. 880, 885, 92 L.Ed. 1055 (1948) ("That reasonable men might derive a meaning from the instructions given other than the proper meaning . . . is probable ") (emphasis added).
Although there may not be great differences among these various phrasings, it is important to settle upon a single formulation for this Court and other courts to employ in deciding this kind of federal question. Our cases, understandably, do not provide a single standard for determining whether various claimed errors in instructing a jury require reversal of a conviction. In some instances, to be sure, we have held that "when a case is submitted to the jury on alternative theories the unconstitutionality of any of the theories requires that the conviction be set aside. See, e.g., Stromberg v. California, 283 U.S. 359 [51 S.Ct. 532, 75 L.Ed. 1117] (1931)." Leary v. United States, 395 U.S. 6, 31-32, 89 S.Ct. 1532, 1545-1546, 23 L.Ed.2d 57 (1969); see also Bachellar v. Maryland, 397 U.S. 564, 571, 90 S.Ct. 1312, 1316, 25 L.Ed.2d 570 (1970). In those cases, a jury is clearly instructed by the court that it may convict a defendant on an impermissible legal theory, as well as on a proper theory or theories. Although it is possible that the guilty verdict may have had a proper basis, "it is equally likely that the verdict . . . rested on an unconstitutional ground," Bachellar, supra, at 571, 90 S.Ct., at 1316, and we have declined to choose between two such likely possibilities.
In this case we are presented with a single jury instruction. The instruction is not concededly erroneous, nor found so by a court, as was the case in Stromberg v. Cailfornia, 283 U.S. 359, 51 S.Ct. 532, 75 L.Ed. 1117 (1931). The claim is that the instruction is ambiguous and therefore subject to an erroneous interpretation. We think the proper inquiry in such a case is whether there is a reasonable likelihood that the jury has applied the challenged instruction in a way that prevents the consideration of constitutionally relevant evidence. Although a defendant need not establish that the jury was more likely than not to have been impermissibly inhibited by the instruction, a capital sentencing proceeding is not inconsistent with the Eighth Amendment if there is only a possibility of such an inhibition. This "reasonable likelihood" standard, we think, better accommodates the concerns of finality and accuracy than does a standard which makes the inquiry dependent on how a single hypothetical "reasonable" juror could or might have interpreted the instruction. There is, of course, a strong policy in favor of accurate determination of the appropriate sentence in a capital case, but there is an equally strong policy against retrials years after the first trial where the claimed error amounts to no more than speculation.  Jurors do not sit in solitary isolation booths parsing instructions for subtle shades of meaning in the same way that lawyers might. Differences among them in interpretation of instructions may be thrashed out in the deliberative process, with commonsense understanding of the instructions in the light of all that has taken place at the trial likely to prevail over technical hairsplitting.
Applying this standard to factor (k) of CALJIC 8.84.1 standing alone, we think there is not a reasonable likelihood that Boyde's jurors interpreted the trial court's instructions to prevent consideration of mitigating evidence of background and character. The jury was instructed, according to factor (k), that "you shall consider . . . [a]ny other circumstance which extenuates the gravity of the crime even though it is not a legal excuse for the crime," and the term "extenuate" was defined by the court to mean "to lessen the seriousness of a crime as by giving an excuse." App. 34. Petitioner contends that this instruction did not permit the jury to give effect to evidence-presented by psychologists, family, and friends-of his impoverished and deprived childhood, his inadequacies as a school student, and his strength of character in the face of these obstacles. But as we explained last Term in Penry v. Lynaugh: " 'evidence about the defendant's background and character is relevant because of the belief, long held by this society, that defendants who commit criminal acts that are attributable to a disadvantaged background, or to emotional and mental problems, may be less culpable than defendants who have no such excuse.' " 492 U.S., at 319, 109 S.Ct., at 2947 (quoting California v. Brown, 479 U.S., at 545, 107 S.Ct., at 841 (O'CONNOR, J., concurring)) (emphasis added). Petitioner had an opportunity through factor (k) to argue that his background and character "extenuated" or "excused" the seriousness of the crime, and we see no reason to believe that reasonable jurors would resist the view, "long held by society," that in an appropriate case such evidence would counsel imposition of a sentence less than death. The instruction did not, as petitioner seems to suggest, limit the jury's consideration to "any other circumstance of the crime which extenuates the gravity of the crime." The jury was directed to consider any other circumstance that might excuse the crime, which certainly includes a defendant's background and character. 
Even were the language of the instruction less clear than we think, the context of the proceedings would have led reasonable jurors to believe that evidence of petitioner's background and character could be considered in mitigation. Other factors listed in CALJIC 8.84.1 allow for consideration of mitigating evidence not associated with the crime itself, such as the absence of prior criminal activity by a defendant, the absence of prior felony convictions, and youth. When factor (k) is viewed together with those instructions, it seems even more improbable that jurors would arrive at an interpretation that precludes consideration of all non-crime-related evidence.
All of the defense evidence presented at the penalty phase four days of testimony consuming over 400 pages of trial transcript-related to petitioner's background and character, and we think it unlikely that reasonable jurors would believe the court's instructions transformed all of this "favorable testimony into a virtual charade." California v. Brown, 479 U.S., at 542, 107 S.Ct., at 840. The jury was instructed that it "shall consider all of the evidence which has been received during any part of the trial of this case," App. 33 (emphasis added), and in our view reasonable jurors surely would not have felt constrained by the factor (k) instruction to ignore all of the evidence presented by petitioner during the sentencing phase. Presentation of mitigating evidence alone, of course, does not guarantee that a jury will feel entitled to consider that evidence. But the introduction without objection of volumes of mitigating evidence certainly is relevant to deciding how a jury would understand an instruction which is at worst ambiguous. This case is unlike those instances where we have found broad descriptions of the evidence to be considered insufficient to cure statutes or instructions which clearly directed the sentencer to disregard evidence. See, e.g., Hitchcock v. Dugger, 481 U.S. 393, 398-399, 107 S.Ct. 1821, 1824-1825, 95 L.Ed.2d 347 (1987) ("[I]t could not be clearer that the advisory jury was instructed not to consider, and the sentencing judge refused to consider, evidence of nonstatutory mitigating circumstances . . ."); Lockett, 438 U.S., at 608, 98 S.Ct., at 2966 (plurality opinion) (Even under Ohio's "liberal" construction of the death penalty statute, "only the three factors specified in the statute can be considered in mitigation of the defendant's sentence").
Petitioner also asserts that arguments by the prosecutor immediately before the jury's sentencing deliberations reinforced an impermissible interpretation of factor (k) and made it likely that jurors would arrive at such an understanding. But arguments of counsel generally carry less weight with a jury than do instructions from the court. The former are usually billed in advance to the jury as matters of argument, not evidence, see Tr. 3933, and are likely viewed as the statements of advocates; the latter, we have often recognized, are viewed as definitive and binding statements of the law. See Carter v. Kentucky, 450 U.S. 288, 302-304, and n. 20, 101 S.Ct. 1112, 1120-1121, and n. 20, 67 L.Ed.2d 241 (1981); Quercia v. United States, 289 U.S. 466, 470, 53 S.Ct. 698, 699, 77 L.Ed. 1321 (1933); Starr v. United States, 153 U.S. 614, 626, 14 S.Ct. 919, 923, 38 L.Ed. 841 (1894). Arguments of counsel which misstate the law are subject to objection and to correction by the court. E.g., Greer v. Miller, 483 U.S. 756, 765-766, and n. 8, 107 S.Ct. 3102, 3109, and n. 8, 97 L.Ed.2d 618 (1987). This is not to say that prosecutorial misrepresentations may never have a decisive effect on the jury, but only that they are not to be judged as having the same force as an instruction from the court. And the arguments of counsel, like the instructions of the court, must be judged in the context in which they are made. Greer, supra, at 766, 107 S.Ct., at 3109; Darden v. Wainwright, 477 U.S. 168, 179, 106 S.Ct. 2464, 2470, 91 L.Ed.2d 144 (1986); United States v. Young, 470 U.S. 1, 11-12, 105 S.Ct. 1038, 1044-1045, 84 L.Ed.2d 1 (1985); see also Donnelly v. DeChristoforo, 416 U.S. 637, 647, 94 S.Ct. 1868, 1873, 40 L.Ed.2d 431 (1974) ("[A] court should not lightly infer that a prosecutor intends an ambiguous remark to have its most damaging meaning or that a jury, sitting through lengthy exhortation, will draw that meaning from the plethora of less damaging interpretations").
We find no objectionable prosecutorial argument in this case. Petitioner maintains that the prosecutor encouraged an intolerably narrow view of factor (k) when he argued to the jury that the mitigating evidence did not "suggest that [petitioner's] crime is less serious or that the gravity of the crime is any less," App. 24, and that "[n]othing I have heard lessens the seriousness of this crime." Id., at 29. But we agree with the Supreme Court of California, which was without dissent on this point, that "[a]lthough the prosecutor argued that in his view the evidence did not sufficiently mitigate Boyde's conduct, he never suggested that the background and character evidence could not be considered." 46 Cal.3d, at 251, 250 Cal.Rptr., at 105, 758 P.2d, at 47. His principal tack was not to contend that background and character were irrelevant, but to urge the jury that despite petitioner's past difficulties, he must accept responsibility for his actions. See App. 28-30. Indeed, the prosecutor explicitly assumed that petitioner's character evidence was a proper factor in the weighing process, but argued that it was minimal in relation to the aggravating circumstances:
"The Defendant can dance. The Defendant . . . may have some artistic talent. The Defendant may, in fact, have been good with children. During the course of twenty-four years, even on a basis of just random luck, you are going to have to have picked up something or done something . . . we can all approve of, but if you consider that on the weight that goes against it, . . . it is not even close." Tr. 4820-4821 (emphasis added).
Defense counsel also stressed a broad reading of factor (k) in his argument to the jury: "[I]t is almost a catchall phrase. Any other circumstance, and it means just that, any other circumstance which extenuates the gravity of the crime even though it is not a legal excuse." App. 31. 
In sum, we conclude there is not a reasonable likelihood that the jurors in petitioner's case understood the challenged instructions to preclude consideration of relevant mitigating evidence offered by petitioner. We thus hold that the giving of the jury instructions at issue in this case, former CALJIC 8.84.1 and 8.84.2, did not violate the Eighth and Fourteenth Amendments to the United States Constitution. The judgment of the Supreme Court of California is Affirmed.
Justice MARSHALL, with whom Justice BRENNAN joins, and with whom Justice BLACKMUN and Justice STEVENS join as to Parts I, II, III, and IV, dissenting.
^1 The complete instruction provides:
"In determining which penalty is to be imposed on [each] defendant, you shall consider all of the evidence which has been received during any part of the trial of this case, [except as you may be hereafter instructed]. You shall consider, take into account and be guided by the following factors, if applicable:
"(a) The circumstances of the crime of which the defendant was convicted in the present proceeding and the existence of any special circumstance[s] found to be true.
"(b) The presence or absence of criminal activity by the defendant which involved the use or attempted use of force or violence or the expressed or implied threat to use force or violence.
"(c) The presence or absence of any prior felony conviction.
"(d) Whether or not the offense was committed while the defendant was under the influence of extreme mental or emotional disturbance.
"(e) Whether or not the victim was a participant in the defendant's homicidal conduct or consented to the homicidal act.
"(f) Whether or not the offense was committed under circumstances which the defendant reasonably believed to be a moral justification or extenuation for his conduct.
"(g) Whether or not the defendant acted under extreme duress or under the substantial domination of another person.
"(h) Whether or not at the time of the offense the capacity of the defendant to appreciate the criminality of his conduct or to conform his conduct to the requirements of law was impaired as a result of mental disease or defect or the affects of intoxication.
"(i) The age of the defendant at the time of the crime.
"(j) Whether or not the defendant was an accomplice to the offense and his participation in the commission of the offense was relatively minor.
"(k) Any other circumstance which extenuates the gravity of the crime even though it is not a legal excuse for the crime."
^2 In People v. Easley, 34 Cal.3d 858, 196 Cal.Rptr. 309, 671 P.2d 813 (1983), the Supreme Court of California stated that in order to avoid potential misunderstanding over the meaning of factor (k) in the future, trial courts "should inform the jury that it may consider as a mitigating factor 'any other circumstance which extenuates the gravity of the crime even though it is not a legal excuse for the crime' and any other 'aspect of [the] defendant's character or record . . . that the defendant proffers as a basis for a sentence less than death.' " Id., at 878, n. 10, 196 Cal.Rptr., at 322, n. 10, 671 P.2d, at 826, n. 10 (quoting Lockett v. Ohio, 438 U.S. 586, 604, 98 S.Ct. 2954, 2964, 57 L.Ed.2d 973 (1978) (plurality opinion)). CALJIC 8.84.1 has since been formally amended and the present factor (k) instruction directs the jury to consider "[a]ny other circumstance which extenuates the gravity of the crime even though it is not a legal excuse for the crime [and any sympathetic or other aspect of the defendant's character or record [that the defendant offers] as a basis for a sentence less than death, whether or not related to the offense for which he is on trial . . .]." 1 California Jury Instructions, Criminal 8.85(k) (5th ed. 1988).
^3 In People v. Brown, 40 Cal.3d 512, 230 Cal.Rptr. 834, 726 P.2d 516 (1986), the Supreme Court of California acknowledged that the "shall impose" language of instruction 8.84.2 "le[ft] room for some confusion as to the jury's role." Id., at 544, n. 17, 230 Cal.Rptr., at 852, n. 17, 726 P.2d, at 534, n. 17. The court believed that the Eighth and Fourteenth Amendments required that the jury have the discretion to decide whether, under all of the relevant circumstances, a defendant deserves the punishment of death or life without parole, id., at 540, 230 Cal.Rptr., at 848, 726 P.2d, at 531, and stated that each case in which the mandatory language was used "must be examined on its own merits to determine whether, in context, the sentencer may have been misled to defendant's prejudice about the scope of its sentencing discretion under the 1978 law." Id., at 544, n. 17, 230 Cal.Rptr., at 852, n. 17, 726 P.2d, at 534, n. 17. The court noted that a proposed instruction, which has since been adopted almost verbatim, see 1 CALJIC 8.88 (5th ed. 1988), would conform to its opinion: " 'The weighing of aggravating and mitigating circumstances does not mean a mere mechanical weighing of factors on each side of an imaginary scale, or the arbitrary assignment of weights to any of them. You are free to assign whatever moral or sympathetic value you deem appropriate to each and all of the various factors you are permitted to consider. In weighing the various circumstances you simply determine under the relevant evidence which penalty is justified and appropriate by considering the totality of the aggravating circumstances with the totality of the mitigating circumstances. To return a judgment of death, each of you must be persuaded that the aggravating evidence [circumstances] is so substantial in comparison with the mitigating circumstances that it warrants death instead of life without parole.' " 40 Cal.3d, at 545, n. 19, 230 Cal.Rptr., at 853, n. 19, 726 P.2d, at 535, n. 19.
^4 In other contexts, we have held that a defendant cannot establish a constitutional violation simply by demonstrating that an alleged trial-related error could or might have affected the jury. To establish that ineffective assistance of counsel violates the Sixth Amendment, for example, a defendant must show a "reasonable probability that, but for counsel's unprofessional errors, the result of the proceeding would have been different." Strickland v. Washington, 466 U.S. 668, 694, 104 S.Ct. 2052, 2068, 80 L.Ed.2d 674 (1984). Deportation of potential defense witnesses does not violate due process unless
"there is a reasonable likelihood that the testimony could have affected the judgment of the trier of fact." United States v. Valenzuela-Bernal, 458 U.S. 858, 874, 102 S.Ct. 3440, 3450, 73 L.Ed.2d 1193 (1982). And failure of the prosecution to disclose allegedly exculpatory evidence to the defense violates due process "only if there is a reasonable probability that, had the evidence been disclosed to the defense, the result of the proceeding would have been different." United States v. Bagley, 473 U.S. 667, 682, 105 S.Ct. 3375, 3383, 87 L.Ed.2d 481 (1985). To receive a new trial based on newly discovered evidence, a defendant must demonstrate that the evidence would more likely than not lead to a different outcome. See INS v. Abudu, 485 U.S. 94, 107, n. 12, 108 S.Ct. 904, 913, n. 12, 99 L.Ed.2d 90 (1988).
^5 The dissent focuses on the terms "gravity" and "seriousness" and argues that background and character evidence has no effect on the seriousness of the crime. But the jury was instructed to consider any circumstance which "extenuates the gravity of the crime even though it is not a legal excuse for the crime" or "lessens the seriousness of a crime as by giving an excuse." The instruction directs the jury to consider "any other circumstance" which might provide such an excuse, and we think jurors would naturally consider background and character as a possible excuse.
At oral argument (though not in his brief), counsel for petitioner also argued that testimony that Boyde won a prize for his dance choreography while in prison showed that he could lead a useful life behind bars, and that the jury must be able to consider that evidence as a mitigating circumstance under our decision in Skipper v. South Carolina, 476 U.S. 1, 106 S.Ct. 1669, 90 L.Ed.2d 1 (1986). Factor (k), he argued, did not allow for such consideration. In Skipper, we held that a capital defendant must be permitted to introduce in mitigation evidence of postcrime good prison behavior to show that he would not pose a danger to the prison community if sentenced to life imprisonment rather than death. The testimony that petitioner had won a dance contest while in prison, however, was introduced not to demonstrate that he was a "model prisoner" like Skipper and therefore unlikely to present a risk of future dangerousness, but to show that he had artistic ability. Tr. 4607-4608. Moreover, although the record is not clear on this point, petitioner apparently won the dance prize during a prison term served prior to the Gibson murder, and the evidence thus did not pertain to prison behavior after the crime for which he was sentenced to death, as was the case in Skipper. The testimony about dancing ability was presented as part of petitioner's overall strategy to portray himself as less culpable than other defendants due to his disadvantaged background and his character strengths in the face of those difficulties. As with other evidence of good character, therefore, the jury had the opportunity to conclude through factor (k) that petitioner's dancing ability extenuated the gravity of the crime because it showed that Boyde's criminal conduct was an aberration from otherwise good character.
^6 We find no merit to the contention of petitioner and amicus that arguments of prosecutors in other California cases bear on the validity of the factor (k) instruction in this case. Petitioner's jury obviously was not influenced by comments made in other California capital trials. Nor do we think the fact that prosecutors in other cases may have pressed a construction of factor (k) that would cause the sentencing proceedings to violate the Eighth Amendment means that reasonable jurors are likely to have arrived at an such an interpretation. Prosecutors are interested advocates, and the arguments that one or more prosecutors may have made in urging a particular construction of factor (k) in other cases is not a weighty factor in deciding whether the jury in petitioner's case would have felt precluded from considering mitigating evidence.