Pamela Samuelson and David R. Hansen have self-archived "Brief of Amici Curiae Academic Authors in Support of Defendant-Appellant and Reversal" in SSRN.
Here's an excerpt:
Summary of argument: Class certification was improperly granted below because the District Court failed to conduct a rigorous analysis of the adequacy of representation factor, as Rule 23(a)(4) requires. The three individual plaintiffs who claim to be class representatives are not academics and do not share the commitment to broad access to knowledge that predominates among academics. . . .
Academic authors desire broad public access to their works such as that which the Google Books project provides. Although the District Court held that the plaintiffs had inadequately represented the interests of academic authors in relation to the proposed settlement, it failed to recognize that pursuit of this litigation would be even more adverse to the interests of academic authors than the proposed settlement was. . . .
In short, a "win" in this case for the class representatives would be a "loss" for academic authors. It is precisely this kind of conflict that courts have long recognized should prevent class certification due to inadequate representation. The District Court failed to adequately address this fundamental conflict in its certification order, though it was well aware of the conflict through submissions and objections received from the settlement fairness hearing through to the hearings on the most recent class certification motions. Because of that failure, the order certifying the class should be reversed