Chief Justice Warren's plurality opinion in Trop v. Dulles holds that the 8th Amendment's prohibition of "cruel and unusual punishments"
must draw its meaning from the evolving standards of decency that mark the progress of a maturing society.Those evolving standards are where constitutional abolitionists try to make their stand. But the 5th Amendment specifically authorizes capital prosecutions and executions.
No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a grand jury, except in cases arising in the land or naval forces, or in the militia, when in actual service in time of war or public danger; nor shall any person be subject for the same offense to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.
And as as Antonin Scalia, who hates Trop the way Ted Cruz hates Obamacare, pointed out in his concurring opinion (responding to Breyer's call for an outright 8th Amendment challenge) in Glossip v. Gross,
It is impossible to hold unconstitutional that which the Constitution explicitly contemplates.
As Farias says,
It's a devastating textualist argument.
I'm not a textualist (though I think the text matters far more than Breyer does, since he believes more in what he imagines the Constitution wants to achieve than in what it actually provides), but I've long understood that conflict to be seriously problematic.
Of course, the problem can be resolved easily enough by the Rule of 5. The Constitution, after all, means only and precisely what 5 members of the Supreme Court say it does. If there are 5 votes to say that the death penalty violates the 8th and is therefore unconstitutional, Scalia's fulminations won't matter. And that's clearly been the hope for nearly 40 years.
But there's another way, the way Harry Blackmun was pointing in Callins v. Collins when he concluded that the death penalty was unconstitutional.
The 8th Amendment requires that the death penalty be imposed fairly, consistently, and reliably. The 5th Amendment says that as long as there's sufficient process, executions are constitutional. Blackmun's epiphany, after his years of "tinkering with the machinery of death" is that the requirements cannot be reconciled. What we've come to learn, what experience has taught, is that the framers expectation cannot be satisfied. No amount of process is sufficient to achieve what the 8th Amendment requires.
Here's Blackmun (footnotes omitted):
From this day forward, I no longer shall tinker with the machinery of death. For more than 20 years I have endeavored — indeed, I have struggled — along with a majority of this Court, to develop procedural and substantive rules that would lend more than the mere appearance of fairness to the death penalty endeavor.1Rather than continue to coddle the Court's delusion that the desired level of fairness has been achieved and the need for regulation eviscerated, I feel morally and intellectually obligated simply to concede that the death penalty experiment has failed. It is virtually self-evident to me now that no combination of procedural rules or substantive regulations ever can save the death penalty from its inherent constitutional deficiencies. The basic question — does the system accurately and consistently determine which defendants "deserve" to die? — cannot be answered in the affirmative. It is not simply that this Court has allowed vague aggravating circumstances to be employed, see, e. g., Arave v. Creech, 507 U. S. 463 (1993), relevant mitigating evidence to be disregarded, see, e. g., Johnson v. Texas, 509 U. S. 350 (1993), and vital judicial review to be blocked, see, e. g., Coleman v. Thompson, 501 U. S. 722 (1991). The problem is that the inevitability of factual, legal, and moral error gives us a system that we know must wrongly kill some defendants, a system that fails to deliver the fair, consistent, and reliable sentences of death required by the Constitution.
It's not the "evolving standards" of the 8th Amendment that the death penalty fails. It's the conditional authorization of the 5th Amendment.
At least, that's one argument.

