Criminal cases create the bulk of American litigation, and ninety percent of them end in guilty pleas.  Thus for the vast majority of accused citizens and eventually for each judge, prosecutor, and defense counsel, sentencing looms as the major concern.  Indeed for many citizens sentencing is their most significant encounter with the criminal-justice system, their only hope of securing the constitutional promise of effective assistance of counsel.
Yet a tragic irony repeats itself each day in American courtrooms.  First those facing sentencing are accompanied by lawyers and judges who by custom and training regard their essential roles to be triers of cases.  Second most sentencing literature labors to convince readers what the law should be, not what it actually is.  Thus in far too many cases courtroom personnel do not know the law of sentencing, are unaware of their responsibilities, and cannot find a source addressing these concerns.
   The irony has intensified since this treatise's first edition, for the 1980s and early '90s brought more change to sentencing law than had occurred in the prior one-hundred years.  Besides thrusting new challenges upon judges and prosecutors, it increased demands upon defense counsel, creating more pitfalls of ineffective-assistance claims.
Unfortunately advances in electronic law-retrieval have compounded the problem.  Although the second edition made extensive use of this tool, such research exposed the computer's limited help in attaining a realistic grasp of the issues.  At best it can only display scattered bits of sentencing law, disregarding their link to crucially related concerns and neglecting entirely their practical impact.
This treatise presents a single authoritative updated volume of current sentencing, plus practical pointers for judges, lawyers, probation officers, and other professionals in this field.  It has completely revised the first edition, which at last count had been cited with approval in over 60 judicial opinions.
Having participated in sentencing as a prosecutor, defense counsel, legislative analyst, and judicial advisor, the author knows this volume can merely offer rules, rationales, and suggestions.  Only when combined in action by conscientious court, counsel, and correctional officials does there exist what can truly be called the law of sentencing.

     Because the death sentence is uniquely severe(1)  and irreversible, the Eighth Amendment's cruel-and-unusual clause requires a commensurate set of safeguards against its inappropriate imposition(2).   Although other constitutional provisions place additional restrictions on sentences of death(3),  the most far-reaching decisions by the United States Supreme Court have been based on the Eighth Amendment(4).

     Since the High Court's landmark examination of death sentences in 1977(5),  essentially three requirements have arisen under the aegis of the Eighth Amendment.First the intrinsic nature of the crime must be shown to merit the sanction of death.  Second in order to avoid arbitrary and capricious imposition, either the death-sentence statute or its implementation must enable sentencers to narrow the death-eligible class and reasonably justify death for the selected offender compared to others found guilty of the same crime.  Third the sentencer must be allowed to consider any mitigating factor that is relevant to the particular offender's case.  Each of these requirements will be examined in turn. 
     Proportionality is the key concept for testing whether the intrinsic nature of the offender's acts merits the death penalty.  The inquiry is whether in light of the Eight Amendment's evolving standards of decency it is disproportional for the acts under scrutiny to carry a death sentence.  In 1977 the United States Supreme Court scrutinized legislation mandating death for raping an adult woman and invalidated the penalty as grossly disproportionate and excessive(6).

     Since then the Court has ruled death disproportional for a felony-murder participant "who does not himself kill, attempt to kill or intend that a killing take place or that lethal force will be used."(7)   Nevertheless, death was held permissible for a "major participant" or one who acted with "reckless indifference" even if the offender did not personally intend to kill or commit the act leading to the victim's demise(8).   The Justices have also held proportionality draws a narrow but constitutional line between offenders who commit first-degree murder at the age of fifteen and sixteen; the former may not receive the death penalty(9)  but the latter may(10).   So also may offenders who are mentally retarded(11). 
     Despite its own use of proportionality in selected cases, the Court has stated appellate review under this test is not constitutionally required in every case(12). 

     We turn next to the second requirement under the cruel-and-unusual clause: that sentencers narrow the class of capital offenders and reasonably justify death for the offender compared to others found guilty of the same crime.  The analysis begins with Furman vs Georgia, a one-paragraph, per-curiam decision invalidating a death-sentence statute before the Court(13). Culling the voluminous non-majority opinions appended to this holding, it appears the legislation's major defect was allowing unfettered jury discretion to determine which of various statutorily eligible offenders received the death sentence. 

     Despite continued plurality opinions concerning this requirement, a consensus seems to have emerged: the Constitution prohibits death imposed by sentencers with unbridled discretion;(14)  in order to minimize this risk of arbitrary and capricious imposition, the sentencing decision must be made under a system of guided discretion(15). 
The Court has authorized two ways of satisfying this constitutional demand.  Legislatures can either provide a sufficiently narrow definition of capital offenses or it can authorize sentencers to narrow the death-eligible class by finding appropriate aggravating factors in the case at hand(16).    Accordingly statutory language may not be so vague as to impair its narrowing purpose(17).   Thus where aggravating factors are used, they must be sufficiently specific-- although the Court's view of sufficiency here has ranged from a record of prior crimes(18)  to psychiatric testimony concerning the offender's propensity for future violence(19).   Once a constitutionally sufficient factor has been determined, there is no harm in allowing sentencers to employ other factors to further narrow the candidates(20).

     Death sentences may not rest even in part upon an invalid aggravating circumstance;(21)  moreover any statute that requires affirming a death sentence in such situation if at least one other valid aggravating circumstance exists would be unconstitutional(22).   Nonetheless the Court itself has upheld death sentences despite jury reliance upon an invalid aggravating factor; in one instance the jury had found another independent valid factor(23),  and in another the valid factor was determined by an appellate court(24). 
     Death-sentencing jurors may not be led to believe responsibility for the offender's death lies elsewhere(25),  but they may be informed of the governor's power to commute their possible alternative sentence of life-without-parole(26).   Though jurors may reconsider their doubts about an offender's character or the circumstances of the crime during the sentencing phase, the offender has no Eighth Amendment right to have them reconsider their prior verdict of the guilt phase(27).   They may also be instructed to ignore "mere sentiment, conjecture, sympathy, passion, prejudice, public opinion, or public feeling," despite the possibility that they might interpret this to ignore evidence "sympathetic" to the offender(28).   On the other hand, the risk of their arbitrary or capricious response is too great if jurors are exposed to a victim-impact statement(29)  or the prosecutor argues the victim's good moral character(30). 

     The third general demand of the Eighth Amendment in death-sentencing cases concerns the admission and effect of mitigating evidence.  In 1977 the United States Supreme Court struck down legislation which mandated death for murdering a police officer or fire fighter; the statute's defect was its failure to allow sentencers to consider "particularized mitigating factors(31)."   Next year the Justices invalidated a statute that contained three specific mitigating factors; in contrast to the Court's allowance of broad aggravating circumstances discussed above, the statute too narrowly limited consideration of mitigating circumstances.  "To meet constitutional requirements, a death penalty statute must not preclude consideration of [other] relevant mitigating factors(32)." 
This demand has been since construed as requiring any relevant mitigating evidence the defense proffers concerning the character or history of the offender or the circumstances of the offense(33).   Failure to do so would impose death sentences without considering their recipients as "uniquely individual human beings(34)."   Specifically, this can require admission of evidence tendered by the defense to show the offender's youth, lack of criminal record, voluntary surrender to authorities, or rehabilitative potential(35).   It can also mandate proffered admission of an offender's favorable record of pretrial incarceration(36).   Or, under the cultural belief that offenders who are influenced by disadvantaged background or emotional or mental problems are less morally culpable than others(37),  it also permits defense evidence of the offender's violent family history and retarded mental and emotional development(38).

     Not only must relevant mitigating evidence be admitted, it must be actually considered(39),  which in appropriate cases means specifically instructing the jury to do so(40).   Although only the jury can determine the significance and weight of aggravating and mitigating factors, it does not unconstitutionally deflect them from this task to instruct them to "consider, take into account and be guided by" certain factors listed in a death-sentence statute(41).   Nor does it unconstitutionally limit their consideration of mitigating evidence when jurors are statutorily required to impose death when they unanimously find at least one aggravating factor and no mitigating factor, or if aggravants outweigh mitigants. 
     So crucial is consideration of relevant mitigating evidence that any death sentence that results from its deliberate exclusion is presumptively invalid(43).   Similarly a statute requiring jury unanimity on its existence has been held invalid(44).   It is thus constitutionally irrelevant whether the barrier to relevant mitigating evidence results from statute, jury instructions, or an evidentiary ruling(45).