Prosecutorial misconduct is one of the significant causes of unfairness in capital sentencing. Because of this, scrutinizing prosecutors’ arguments, particularly their closing arguments during the penalty phase of capital trials, is an appropriate area of inquiry. The prosecutor’s closing argument at the penalty trial of a capital case is especially significant because it will be the last words that the sentencing jury hears from either attorney. This impact will be magnified by the lack of clear sentencing guidelines. The decision whether to sentence the defendant to death generally depends on weighing broadly defined aggravating and mitigating circumstances. Evidence has shown that, even when the jury receives proper instructions from the judge, members are likely to be confused as to the criteria that should be employed in making the sentencing decision. There is some support for imposing per se prohibitions on particular categories of prosecutors’ arguments. A prosecutor’s argument that violates the prohibition will either automatically preclude the imposition of the death penalty or at least preclude it when defense counsel objects to the argument. Courts will deter prosecutors from making improper penalty trial arguments and will also reduce the possibility that defendants will be sentenced to death as a result of such arguments. The criteria for establishing prohibitions on prosecutor’s penalty trial arguments include when an improper argument seems reasonably likely to deflect the jury from making an individualized sentencing decision. The four categories of prosecutors’ penalty trial arguments that should be subject to prohibition are (1) misleading the jury as to the circumstances under with the defendant will be released from prison; (2) relying upon a religious text in support of imposing the death penalty; (3) referring to the prosecutor’s discretionary decision to seek the death penalty; and (4) arguing that the death penalty should be imposed to protect society rather than for reasons related to the facts of the case. 209 footnotes