"....The Constitution structures the National Government, confines its actions, and, in regard to certain individual liberties and other specified matters, confines the actions of the States. With a few exceptions, such as the provisions of the Thirteenth Amendment, constitutional guarantees of individual liberty and equal protection do not apply to the actions of private entities. Tarkanian, supra, 488 U.S., at 191, 109 S.Ct., at 461; Flagg Bros, Inc. v. Brooks, 436 U.S. 149, 156, 98 S.Ct. 1729, 1733, 56 L.Ed.2d 185 (1978). This fundamental limitation on the scope of constitutional guarantees "preserves an area of individual freedom by limiting the reach of federal law" and "avoids imposing on the State, its agencies or officials, responsibility for conduct for which they cannot fairly be blamed." Lugar v. Edmondson Oil Co., 457 U.S. 922, 936-937, 102 S.Ct. 2744, 2753, 73 L.Ed.2d 482 (1982). One great object of the Constitution is to permit citizens to structure their private relations as they choose subject only to the constraints of statutory or decisional law. ...