When Justices Scalia and Thomas have a broader view of the rights of the accused than the other Justices.

Indiana v. Edwards, decided today, is one of those unusual cases where Justice Scalia (joined by Justice Thomas) has a broader view of the rights of the accused than the other Justices:

The Constitution guarantees a defendant who knowingly and voluntarily waives the right to counsel the right to proceed pro se at his trial. Faretta v. California, 422 U. S. 806 (1975). A mentally ill defendant who knowingly and voluntarily elects to proceed pro se instead of through counsel receives a fair trial that comports with the Fourteenth Amendment. Godinez v. Moran, 509 U. S. 389 (1993). The Court today concludes that a State may nonetheless strip a mentally ill defendant of the right to represent himself when that would be fairer. In my view the Constitution does not permit a State to substitute its own perception of fairness for the defendant’s right to make his own case before the jury –a specific right long understood as essential to a fair trial. ...

Edwards wished to take a self-defense case to the jury. His counsel preferred a defense that focused on lack of intent. Having been denied the right to conduct his own defense, Edwards was convicted without having had the opportunity to present to the jury the grounds he believed supported his innocence. I do not doubt that he likely would have been convicted anyway. But to hold that a defendant may be deprived of the right to make legal arguments for acquittal simply because a state-selected agent has made different arguments on his behalf is, as Justice Frankfurter wrote in Adams, to “imprison a man in his privileges and call it the Constitution.” In singling out mentally ill defendants for this treatment, the Court’s opinion does not even have the questionable virtue of being politically correct. At a time when all society is trying to mainstream the mentally impaired, the Court permits them to be deprived of a basic constitutional right—for their own good.

So you can see that Scalia and Thomas conceive of the right more in terms of individual autonomy, while the rest of the Court is willing to reason more flexibly about fairness. There's quite a bit of talk about "dignity," which is said to underlie the right of self-representation, and Justice Breyer, writing for the majority, says:

[A] right of self-representation at trial will not “affirm the dignity” of a defendant who lacks the mental capacity to conduct his defense without the assistance of counsel.... [T]he spectacle that could well result from his self-representation at trial is at least as likely to prove humiliating as ennobling.

When can the judge save a man from himself?