I concur in the result reached by Justice Zimmerman’s opinion and for the most part with his reasons, except as to his concurrence with Justice Durham on the issue of shackling. On that point I concur with Chief Justice Hall. I would, however, give somewhat more credence than Justice.Zimmerman does to the studies suggesting that death-qualified juries are more likely to be conviction prone than non-death-qualified juries. Nevertheless, I believe that if a trial judge allows a sensitive and searching voir dire, conviction-prone persons can be weeded out. Although that task is difficult, it presents fewer difficulties than the remedy suggested by Justice Durham. I also agree with Justice Zimmerman that the propensity of the Legislature to continually add new aggravating circumstances to the definition of capital homicide raises difficult problems for the courts and that a judicial narrowing of some of those aggravating circumstances may be constitutionally necessary, but I do not believe that the Utah capital homicide statute is unconstitutional.
In addition, I address the role that sympathy and compassion should play in the penalty phase of a capital case because I would go somewhat further than does Justice Durham.
I. ROLE OF SYMPATHY IN DETERMINING PENALTY IN CAPITAL CASE
I agree with Justice Durham’s conclusion that the trial court should not have instructed the jury in the penalty phase that it could not be swayed by “mere sentiment ... [or] sympathy” for defendant. However, in my view, the reason that the instruction was wrong is that it did not properly state when sympathy could be used and when it could not.
It is contrary to the most fundamental values upon which this society is built to bar a sentencing authority from employing a sympathetic evaluation of mitigating evidence in assessing the moral responsibility of a defendant when deciding whether to take the life of a citizen as punishment for a capital crime. The jury is typically instructed that sympathy is not appropriate in determining the guilt of the defendant. To avoid confusion and ensure clarity in instructions in the penalty phase, an instruction telling the jury that it can make a sympathetic evaluation of the mitigating evidence is not only appropriate, but essential. A sympathetic evaluation of the mitigating evidence is required if the mitigating evidence is to have any relevance to the moral responsibility of the defendant. I believe that result is required by State v. Wood, 648 P.2d 71, 80-85 (Utah), cert. denied, 459 U.S. 988, 103 S.Ct. 341, 74 L.Ed.2d 383 (1982), and State v. Holland, 111 P.2d 1019, 1026-28 (Utah 1989), and by our general responsibility to ensure that instructions in every case adequately inform the jury of how it should reach a proper result.
Accordingly, I submit that a jury should be affirmatively instructed that a sympa*419thetic or empathetic evaluation of the mitigating evidence may be appropriate and relevant to the issue of the defendant’s moral culpability. It is, after all, the issue of the extent of the defendant’s moral culpability that the jury must decide in determining whether a life or a death sentence is appropriate. If a jury is not allowed to make a sympathetic evaluation of the mitigating evidence, that evidence loses its relevance to and its meaning for the critical issue to be decided.1
The Utah capital punishment sentencing procedure presumes that a life sentence, not the death penalty, is the appropriate sentence in a capital homicide case. It follows that the State has the burden of convincing a jury that the death penalty is the only appropriate penalty. See State v. Pierre, 572 P.2d 1338, 1347-48 (Utah 1977), cert. denied, 439 U.S. 882, 99 S.Ct. 219, 58 L.Ed.2d 194 (1978). The capital homicide sentencing statute, Utah Code Ann. § 76— 3-207(2), provides that evidence as to “the defendant’s character, background, history, mental and physical condition, and any other facts in ... mitigation of the penalty” may be adduced at the penalty hearing.2 Indeed, that is required under the Constitution of the United States. Eddings v. Oklahoma, 455 U.S. 104, 113-15, 102 S.Ct. 869, 876-77, 71 L.Ed.2d 1 (1982); Lockett v. Ohio, 438 U.S. 586, 604-09, 98 S.Ct. 2954, 2964-67, 57 L.Ed.2d 973 (1978) (plurality opinion); Woodson v. North Carolina, 428 U.S. 280, 303-04, 96 S.Ct. 2978, 2990-91, 49 L.Ed.2d 944 (1976) (plurality opinion); see also California v. Brown, 479 U.S. 538, 541, 107 S.Ct. 837, 839, 93 L.Ed.2d 934 (1987). That is also implicit in our case law. See State v. Holland, 777 P.2d at 1026-28; State v. Wood, 648 P.2d at 80-85.
Although defendant’s proposed instruction No. 5 could have been framed more artfully, it, or something similar, should have been given in the penalty phase. That instruction stated:
In the guilt phase of this case, you were instructed that you should not base your verdict on various irrelevant matters, including sympathy.
You are now instructed that sympathy does play a legitimate part in the determination of whether a defendant shall suffer death or serve a life sentence in prison.
If after consideration of all the circumstances, you feel sympathy for the defendant that is based on the evidence you have heard, and based on such sympathy you are inclined to extend mercy to the *420defendant, the law enables you to act upon such sympathy and fix the penalty at life imprisonment.3
(Emphasis in original.)
It is important to delineate precisely what such an instruction would and would not allow the jury to do. First, it has no place in the determination of guilt and therefore would not allow a jury to exonerate or pardon a defendant for the crime he committed. Second, the instruction would not allow the jury to act in a mindless, irrational, or emotional fashion; it does not make sympathy in and of itself a mitigating factor. Third, the instruction makes explicit that the jurors’ sympathy must be based on the evidence, namely, the mitigating evidence submitted by the defendant. Fourth, whatever sympathy the mitigating evidence evokes can be used only to decide which penalty to impose, not whether a penalty should be imposed. What the instruction does is to tell the jury that weighing mitigating and aggravating circumstances is not a sterile mathematical or mechanical process and that the jury should not impassively dismiss whatever significance and meaning the defendant’s past experiences have to the issue of which punishment to impose. In short, the jurors are not to take leave of their humanity at the courthouse doors. Nor should they act like robots with respect to evidence' that has relevance only when understood in human terms.
If a jury is to properly perform its critical constitutional function under the standards stated in Wood and Holland, it must understand what is meant by the term “mitigating circumstances” and how it should deal with them. A sympathetic response to mitigating evidence for the purpose of addressing the degree of moral responsibility does not invite caprice or irrationality. On the contrary, for the jury to act morally and legally in assessing the mitigating evidence, it must act with sympathetic, human understanding. The psychology of child development has long recognized that children do not learn moral conduct simply by rational means. A sense of sympathy is absolutely essential to the development of moral human conduct. Psychopaths use reason well, but their moral capacity is lacking because they do not have the ability to empathize and sympathize. Mature adults cannot exercise moral judgment about others without a sympathetic or empathetic response to those whom they judge. Certainly it is not possible for jurors to perform their constitutional tasks by totally forsaking their sympathetic sensibilities.
No sharp line differentiates between rational understanding and sympathy with respect to the capacity to make moral judgments. The law has long recognized that both qualities are essential to proper judgment and has accorded sympathy an established role in the criminal justice system. In non-capital crimes, judges in granting probation and parole and the Board of Pardons in fixing the length of prison terms are, and ought to be, sympathetically sensitive to mitigating factors that bear on the degree of a criminal’s moral culpability.
In short, sympathy is a means whereby jurors seek to understand and give human meaning to the “facts” of a defendant’s “character, background, history, [and] mental and physical condition” for the purpose of assessing the degree of the defendant’s moral culpability. It is both senseless and illogical to say that the jury must hear mitigating evidence, but that it can give no meaning to that evidence based on a sympathetic evaluation of it. To contend otherwise is to say that the jury must “weigh” the aggravating evidence against the mitigating evidence, which has been shorn of relevant meaning. The reason for allowing the defendant to present mitigating evidence is to provide the jury with a basis for exercising a moral judgment. See Wood, 648 P.2d at 83-84. To do that, the jurors *421must be able to respond to that evidence in a manner that reflects mature moral judgment. In short, jurors should be encouraged to seek to understand, based on their understanding of human nature, the mind and the heart of the defendant and his moral capacity. That does not mean that a jury, once it understands the defendant’s evidence, will necessarily vote for a life sentence or act capriciously. To understand is not necessarily to condone or justify-
The judicial system need not subscribe to a philosophy of Determinism to recognize, for example, that a defendant who has been brutally, cruelly, and constantly abused physically, emotionally, and sexually as a child and teenager is not likely to have the self-discipline and moral standards of those reared in better circumstances, or that a woman who is viciously and repeatedly battered for years by a brutally abusive husband may react violently in what she subjectively thinks is self-defense, even though that defense is not available under the objective standards of the law. In imposing a penalty, surely a jury is entitled to treat such persons differently from a contract killer, a Mafia assassin, or a terrorist who bombs a commercial airliner in flight.
In Wood, we made clear that the process of “weighing” mitigating circumstances against aggravating circumstances in the penalty phase is an imprecise and somewhat misleading metaphor. 648 P.2d at 84. In Holland, we stated, “There is a tendency to deal with the aggravating and the mitigating factors in a mechanical fashion.” 777 P.2d at 1027. That point gave rise to our emphasis on the importance of the second part of the Wood test:
To avoid having the first part of the Wood test produce an unduly broad application of the ultimate sanction, Wood also requires the sentencing authority to take a long, hard second look at the totality of the circumstances in light of societal values and the high value that this state and the Eighth Amendment place on the value of all human life and the humanity of every human being, no matter how depraved he or she may have become or how far he or she may have fallen from the norms of a civilized society. It is in applying the second part of the test that the sentencing authority may rely on leniency to refuse to impose the death penalty, “[ejven in the face of overwhelming aggravating evidence_” Satterwhite v. Texas, 486 U.S. 249, [261-62] 108 S.Ct. 1792, 1800, 100 L.Ed.2d 284 (1988) (Marshall, J., concurring). After considering all aspects of the case, in addition to the particular aggravating and mitigating circumstances relied on by the State and the defendant, the sentencing authority must be persuaded beyond a reasonable doubt that the imposition of the death penalty is “justified and appropriate” in the circumstances. Wood, 648 P.2d at 84. Thus, the sentencing authority may refuse to impose the death penalty even though it concedes that the aggravating circumstances “outweigh” the mitigating circumstances beyond a reasonable doubt.
Id. at 1028 (emphasis added).
Denying the jury the right to rely on sympathy and compassion is simply inconsistent with the right of the jury under Holland to use “leniency to refuse to impose the death penalty, [e]ven in the face of overwhelming aggravating evidence.” Id. (quoting Satterwhite v. Texas, 486 U.S. 249, 108 S.Ct. 1792, 100 L.Ed.2d 284 (1988) (Marshall, J., concurring)). Leniency, if deemed appropriate by a jury, will not undermine the safety of society. Society can protect itself by imprisoning dangerous people for life.4
The crime committed in the instant case was cruel and heinous, and the jury im*422posed the death sentence. Perhaps, after a second penalty hearing, the decision will be the same. But that decision can be made only after the jury has had the opportunity to give proper consideration to the mitigating circumstances that defendant adduced in the penalty phase.5
Finally, both Chief Justice Hall and Justice Durham discuss at length the United States Supreme Court cases of California v. Brown, 479 U.S. 538, 107 S.Ct. 837, 93 L.Ed.2d 934 (1987) and Saffle v. Parks, 494 U.S. 484, 110 S.Ct. 1257, 108 L.Ed.2d 415 (1990). In my view, those cases do not control this case. In Brown, the United States Supreme Court held that the California Supreme Court had erred in holding that an antisympathy instruction violated the Eighth and Fourteenth Amendments to the United States Constitution. The instruction there prohibited the jury from employing “mere sympathy.” That decision does not bar a sympathy instruction such as the one discussed above.
Saffle is a decision about the scope of federal habeas corpus law and the federal rule that those courts may not fashion a new rule of law in a habeas case. The holding of Saffle is that an antisympathy instruction does not violate the rule set down by Lockett v. Ohio, 438 U.S. 586, 98 S.Ct. 2954, 57 L.Ed.2d 973 (1978), and Eddings v. Oklahoma, 455 U.S. 104, 102 S.Ct. 869, 71 L.Ed.2d 1 (1982), that a court must admit, and a sentencer must consider, mitigating circumstances. The instruction in Saffle did not tie the role of sympathy to the evaluation of mitigating evidence, as I have indicated should be done.
II. THE WOOD INSTRUCTION
The trial court’s instruction on the application of the Wood standards was erroneous. Instruction No. 7 improperly merged the two prongs of the Wood standard.
III. REBUTTAL ARGUMENT IN THE PENALTY PHASE
Under the procedure outlined by Utah Code Ann. § 76-3-207,1 do not believe that the prosecution is entitled to rebuttal argument in the penalty hearing. That statute does not contemplate it. At the end of the penalty hearing, if there is no rebuttal, the prosecutor will already have argued to the jury three times at the guilt phase and *423twice at the penalty phase. Defense counsel will have argued twice at the guilt phase and twice at the penalty phase. Although the prosecutor surely should have the opportunity to adduce rebuttal evidence, there is no need to provide rebuttal argument. The rules of criminal procedure do not address the problem. Since the primary issue is the extent of comparative moral culpability, and not primarily a factual issue, it is sufficient and fair for each side to address the jury once on closing argument.
IV. ADDITIONAL STATUTORY AGGRAVATING CIRCUMSTANCE IN THE PENALTY PHASE
It was error for the State to insinuate for the first time at the penalty hearing the statutory aggravating circumstance stated in Utah Code Ann. § 76-5-202(1)(q) (1990) as a basis for imposing the death penalty. See State v. Carter, 776 P.2d 886 (Utah 1989). The State cannot argue a statutory aggravating circumstance in the penalty phase that it did not assert in the guilt phase. Basic fairness precludes such a disingenuous tactic. The evidence as to the nature of the crime was before the jury, and the prosecution argued it effectively, but asserting a new statutory aggravating circumstance into the penalty hearing is a recipe for confusion and error.
. It is essential to note that the Legislature has abolished the common law defense of insanity that absolved a defendant of criminal liability if he did not know right from wrong or acted pursuant to an irresistible impulse. Compare Utah Code Ann. § 76-2-305 (1990 & Supp.1992) with State v. Holt, 22 Utah 2d 109, 111, 449 P.2d 119, 120 (1969) and State v. Poulson, 14 Utah 2d 213, 215-16, 381 P.2d 93, 94-95 (1963). The common law defense of insanity drew a sharp distinction between those who were thought to be both morally and legally culpable and those who were not. The consequence of a successful insanity defense under that law was an acquittal. Under present law, the issue of the defendant’s moral culpability, as opposed to his legal culpability, is largely deferred to the penalty phase. Whether a convicted defendant has diminished moral culpability, no moral culpability, or full moral culpability determines whether the defendant should receive a life or a death sentence.
Because mental illness can affect moral culpability, as the capital sentencing statute expressly provides, Utah Code Ann. § 76-3-207(2)(d), I concur with Justice Durham that the jury should be required, when appropriate, to determine whether a defendant is guilty and mentally ill.
. Utah Code Ann. § 76-3-207(2) states:
Mitigating circumstances shall include the following:
(a) The defendant has no significant history of prior criminal activity;
(b) The murder was committed while the defendant was under the influence of extreme mental or emotional disturbance;
(c) The defendant acted under extreme duress or under the substantial domination of another person;
(d) At the time of the murder, the capacity of the defendant to appreciate the criminality (wrongfulness) of his conduct or to conform his conduct to the requirement of law was substantially impaired as a result of mental disease, intoxication, or influence of drugs;
(e) The youth of the defendant at the time of the crime;
(f) The defendant was an accomplice in the murder committed by another person and his participation was relatively minor;
(g) And any other fact in mitigation of the penalty.
. Instead of telling the jury it could "feel sympathy for the defendant,” the instruction should have told the jury that if a sympathetic or empathetic evaluation of the mitigating evidence showed a significantly reduced moral capacity and restraint, the jury should consider that as a factor in favor of a life sentence. See State v. Sessions, 645 P.2d 643, 645 (Utah 1982) (diminished capacity partial defense).
. In capital homicide cases, prosecutors often argue that defendants should be executed because they are likely to be paroled, or might be, and will surely kill again. That argument is disingenuous, unprofessional, and improper and should be prohibited by all trial judges. It assumes that the Board of Pardons will not keep those who are a danger to others in prison, for life if necessary. Nothing in the history of the state of Utah indicates that the Board has been remiss in its duty.
. Defense counsel's closing argument referred to some of the mitigating evidence in this case:
David's defects are severe. His brain is damaged. It’s abnormal. He has pervasive developmental disorder, organic personality syndrome, he has borderline intelligence, and other mood disorders. He was diagnosed by each Doctor, uncontested, unrebutted by the State. What does Mr. Shepherd [the prosecutor] say to you about these things? What is he asking of you? That you ignore this evidence? That this evidence—oh, never mind, not that big of a deal, it really doesn’t have anything to do with David the murderer.
Ladies and gentlemen, that is why we are here. It has everything to do with David the murderer. It is the guts upon which you base a decision whether or not to kill him. What kind of a person is he? What is it Mr. Shepherd is asking you to do? To ignore that David had severe disturbance in thinking and mood? To ignore his inability, utter inability to modulate his own behavior and emotion? To ignore his impaired judgment, and his impulsivity? To ignore his cognitive deficits that he can’t reason, he can’t problem solve, he doesn't know what to do with new information? To ignore organic brain damage? To ignore a CAT scan that shows that part of his brain has turned to bone? To ignore the fact that perhaps fifty years ago he might have qualified for a lobotomy? To ignore the fact that this person’s cognitive age is nine to twelve? And his emotional age is somewhere between six and nine? To ignore the fact that he has autistic similarities, he’s got a vacuum in his conscience, he can’t relate to people? Is this a polite request to ignore evidence simply because he doesn’t like it? Evidence he failed to challenge, he failed to dispute, he failed to rebut, even though it is his burden?
Is he asking you to ignore Doctor Lebegue’s testimony? David’s mental illness obviously enters into all of his actions. Is he asking you to ignore Doctor Lebegue’s testimony that all of these homicides were a product of rage reaction? Is he asking you to ignore that but for David’s brain damage, these homicides would not have occurred? Let’s make something very clear here. This is not a case about comparing David to other brain damaged people, and saying, they didn’t turn out to be murderers. This is a case about comparing murderers to other [murderers] and making a decision about which murderer should die. We kill murderers for acts that are commensurate with their ability to control themselves, to control their behavior.