Caitlin Halligan argued on behalf of the State of New York (argument is here). She is an Obama nominee to the D.C. Circuit (and apparently authored a law school note that may or may not be controversial). This is not to imply an objection to her candidacy, but to note her experience in Indian law.

Update: Ironically, even Ms. Halligan declined to take advantage of Justice O’Connor’s suggestion that tribal sovereignty could be lost through the passage of time. Here is the beginning of her argument:

Argument of Caitlin J. Halligan

Mr. Halligan: Justice Stevens, may it please the Court:

The state of New York was granted time to address the third question regarding the 1838 treaty which we believe requires reversal of the decision below because it disestablish the Oneida reservation.

Respondents claim that there is not exercised sovereignty over any part of land they buy within a vast 300,000 tract in Central new York.

This has long been inhabited–

Justice O’Connor: Is sovereignty something that the tribes can lose by inaction over a period of time?

Mr. Halligan: –I believe that it is, Your Honor, for the reasons that are laid out in petitioner’s brief but regardless of what the Court decides about that question, the Treaty of 1838 clearly disestablishes the reservation which terminates all sovereignty prospectively.

The argument from there is largely treaty-based.