'If a plaintiff could choose the substantive rules to be applied to an action . . . the invitation to forum shopping would be irresistible.' Allstate Ins. Co. v. Hague, 449 U. S. 302, 337 (1981). (opinion of POWELL, J.). Even if a plaintiff evidences his desire for forum law by moving to the forum, courts have generally accorded such a move little or no significance. John Hancock Mut. Life Ins. Co. v. Yates, 299 U. S. 178, 299 U. S. 182 (1936); Home Ins. Co. v. Dick, 281 U. S. 397, 281 U. S. 408 (1930). In Allstate, the plaintiff's move to the forum was only relevant because it was unrelated and prior to the litigation. 449 U.S. at 449 U. S. 318-319.
The issue of personal jurisdiction over plaintiffs in a class action is entirely distinct from the question of the constitutional limitations on choice of law; the latter calculus is not altered by the fact that it may be more difficult or more burdensome to comply with the constitutional limitations because of the large number of transactions which the State proposes to adjudicate and which have little connection with the forum. ...