In written form, that notion of what the right to counsel is looks like this:
[The Sixth Amendment] commands, not that a trial be fair, but that a particular guarantee of fairness be provided—to wit, that the accused be defended by the counsel he believes to be best. “The Constitution guarantees a fair trial through the Due Process Clauses, but it defines the basic elements of a fair trial largely through the several provisions of the Sixth Amendment , including the Counsel Clause.” Strickland, supra, at 684–685. In sum, the right at stake here is the right to counsel of choice, not the right to a fair trial; and that right was violated because the deprivation of counsel was erroneous. No additional showing of prejudice is required to make the violation “complete.”
Alito pens the dissent (and is joined by the Chief and Justices Kennedy and Thomas):
The majority states that the Sixth Amendment protects “the right of a defendant who does not require appointed counsel to choose who will represent him.”What the Sixth Amendment actually protects, however, is the right to have the assistance that the defendant’s counsel of choice is able to provide. It follows that if the erroneous disqualification of a defendant’s counsel of choice does not impair the assistance that a defendant receives at trial, there is no violation of the Sixth Amendment.
In those italics, I hear Scalia being scolded: I thought you were the big textualist. The word "assistance" or one of its variants appears 19 times in Alito's (relatively short) opinion. The count for Scalia (whose opinion is slightly longer): 8.