For years now, some have argued that if substantive due process prohibits disproportionately large punitive damages awards against major corporations, it also should stop courts from enforcing excessive contract damages against consumers. See Seana Valentine Shiffrin, Are Credit Card Late Fees Unconstitutional?, 15 Wm. & Mary Bill Rts. J. 457, 460 (2006).
Two Ninth Circuit judges -- Nelson and Reinhardt -- just endorsed that view. See In re Late Fee and Over-Limit Fee Litigation, 2014 WL 211729.