Exxon Mobil Corporation v. City of New York

(1) Whether a claim is ripe when it is predicated on a plaintiff"s potential future injury and mere good faith intent to take steps in fifteen to twenty years that could, depending on a chain of uncertain events, cause the plaintiff to suffer an actual injury some day in the future; and (2) whether the federal oxygenate mandate in the Clean Air Act Amendments of 1990, 42 U.S.C. § 7545, preempts a state-law tort award that imposes retroactive liability on a manufacturer for using the safest, feasible means available at the time for complying with that mandate.