In this case, the Court held that stripping someone of U.S. citizenship as a punishment for desertion was "cruel and unusual punishment" because the punishment was out of proportion to the crime. Chief Justice Warren drew attention to the flexibility of the words "cruel and unusual."
From the opinion of the Court by Chief Justice Earl Warren:
The exact scope of the constitutional phrase "cruel and unusual" has not been detailed by this Court. But the basic policy reflected in these words is firmly established in the Anglo-American tradition of criminal justice. The phrase in our Constitution was taken directly from the English Declaration of Rights of 1688, and the principle it represents can be traced back to the Magna Carta. The basic concept underlying the Eighth Amendment is nothing less than the dignity of man. While the State has the power to punish, the Amendment stands to assure that this power be exercised within the limits of civilized standards. Fines, imprisonment and even execution may be imposed depending upon the enormity of the crime, but any technique outside the bounds of these traditional penalties is constitutionally suspect. This Court has had little occasion to give precise content to the Eighth Amendment, and, in an enlightened democracy such as ours, this is not surprising. But when the Court was confronted with a punishment of twelve years in irons at hard and painful labor imposed for the crime of falsifying public records, it did not hesitate to declare that the penalty was cruel in its excessiveness and unusual in its character. Weems v. United States, 217 U.S. 349. The Court recognized in that case that the words of the Amendment are not precise, and that their scope is not static. The Amendment must draw its meaning from the evolving standards of decency that mark the progress of a maturing society.