From Rent-A-Center, W., Inc. v. Jackson, 2010 U.S. LEXIS 4981 (U.S. June 21, 2010)(note: the substantive holding of this case is discussed in our post of June 23, 2010):

In his brief to this Court, Jackson made the contention, not mentioned below, that the delegation provision itself is substantively unconscionable because the quid pro quo he was supposed to receive for it — that "in exchange for initially allowing an arbitrator to decide certain gateway questions," he would receive "plenary post-arbitration judicial review" — was eliminated by the Court's subsequent holding in Hall Street Associates, L. L. C. v. Mattel, Inc., 552 U.S. 576, 128 S. Ct. 1396, 170 L. Ed. 2d 254 (2008), that the nonplenary grounds for judicial review in § 10 of the FAA are exclusive. *** He brought this challenge to the delegation provision too late, and we will not consider it.

[Footnote 5] Hall Street Associates, L. L. C. v. Mattel, Inc., 552 U.S. 576, 128 S. Ct. 1396, 170 L. Ed. 2d 254 (2008), was decided after Jackson submitted his brief to the Ninth Circuit, but that does not change our conclusion that he forfeited the argument. Jackson could have submitted a supplemental brief during the year and a half between this Court's decision of Hall Street on March 25, 2008 and the Ninth Circuit's judgment on September 9, 2009. Moreover, Hall Street affirmed a rule that had been in place in the Ninth Circuit since 2003. Id., at 583-584, 128 S. Ct. 1396, 170 L. Ed. 2d 254, and n. 5.