RE: She has no choice in the matter. The Chief Justice will compell her.
Does the law allow John Roberts to do that?
This Wikipedia article summarizes things very well. The law requires recusal and Elena KegFace will have to recuse herself as Justice Sotomayor did in a case which involved Green-House gases where she did work on. The precedent is there. Her colleagues will compel her if she doesn't.:
http://en.wikipedia.org/wiki/Recusal