In De Canas v. Bica, 424 U.S. 351, 354 (1976), the Supreme Court outlined three ways in which state statutes related to immigration may be preempted: if the state statute actually regulates immigration, id. at 354-55; if it was the "clear and manifest purpose of Congress" to preclude even "harmonious state regulation touching on aliens in general," id. at 356-58; if the state law "stands as an obstacle to the accomplishment and execution of the full purpose and objectives of Congress," id. at 363. The Court held that "But the Court has never held that every state enactment which in any way deals with aliens is a regulation of immigration and thus per se pre-empted by this constitutional power, whether latent or exercised." Id. at 355. In DeCanas, the Supreme Court found no "specific indication in either the wording or the legislative history of the INA Immigration and Naturalization Act that Congress intended to preclude even harmonious state regulation touching on aliens in general . . . ." Id. at 358. The United States Supreme Court held that a state statute related to immigration is preempted by federal law if it is a regulation of immigration, which is essentially a "determination of who should or should not be admitted into the country. . .," or if it attempts to regulate a subject matter with respect to which Congress has intended to completely oust state power. Such a congressional intention to occupy the field of law on a particular subject matter may be inferred where the system of federal regulation is so pervasive that no opportunity for state activity remains. ( Id. at p. 357 96 S. Ct. at pp. 937-938.)