The Death Penalty is different than other punishments; it is terminal. 

In Furman v. Georgia, 408 U.S. 238 (1972), the United States Supreme Court held that the imposition of the death penalty as administered in Georgia at that time was "cruel and unusual punishment" in violation of the 8th and 14th Amendments to the U.S. Constitution.  In a single blow, the Furman Court struck down hundreds of state laws deemed "arbitrary and capricious." 

Since that decision, the death penalty has been reinstated by the Supreme Court in 1976, in Gregg v. Georgia.  The majority in Gregg argued that "clear and objective standards" would minimize juror caprice and reduce discrimination (race).  The opinion asserted that, "No longer can a jury wantonly and freakishly impose the death sentence; it is always circumscribed by the legislative guidelines."

Despite such efforts to "tinker with the machinery of death," as Justice Harry Blackmun declared in [Callin v. Collins 1994], growing numbers of Americans have begun to question the rationality of the system that executes people in their name.  The overwhelming number of those put to death or on death row, are poor, uneducated, a member of a minority group, and/or of questionable sanity.

Indeed, after almost 35 years and more than 1,173 executions later, the legal controversy surrounding the death penalty continues unabated.  Most recently, California and several other states have declared a moratorium on the death penalty, pending review of the issue of the whether the protocol of the administration of a lethal injection is "cruel and unusual punishment."

Finally, there is the furor that the Presiding Judge of the Texas Court of Criminal Appeals, Judge Sharon Keller, caused in the case of Michael Richard, who was executed in 2007, several hours after she instructed a court clerk to inform defense attorneys who had requested that the clerk's office remain open past 5:00 pm because they were late in filing a last minute appeal in Mr. Richard's behalf, that the clerk's office closed at 5:00 p.m.  Mr. Richard was executed hours later, without the opportunity to have the issue of whether the method of execution by lethal injection was 'cruel and unusual punishment.'

"From this day forward, I no longer shall tinker with the machinery of death... I feel morally and intellectually obligated to concede that the death penalty experiment has failed," Justice Harry Blackmun (Callin v. Collins 1994).