Potter Stewart

“ To try a defendant in a community that has been exposed to publicity highly adverse to the defendant is per se ground for reversal of his conviction; no showing need be made that the jurors were in fact prejudiced against him. ”

“ Georgia, 385 U.S. 545, 87 S.Ct. 643, 17 L.Ed.2d 599, it has never been suggested that reversal of convictions because of purposeful discrimination in the selection of grand and petit jurors turns on any showing of prejudice to the defendant.
To be sure, constitutional rights are not fungible goods. The differing values which they represent and protect may make a harmless-error rule appropriate for one type of constitutional error and not for another. I would not foreclose the possibility that a harmless-error rule might appropriately be applied to some constitutional violations. ”

“ Reversal is required when a conviction may have been rested on a constitutionally impermissible ground, despite the fact that there was a valid alternative ground on which the conviction could have been sustained. ”