AZ Immigration Law, a preliminary look

Paul at Powerline looks at Arizona's new immigration law:

As I understand it, this is not a situation where Arizona has enacted immigration legislation that's inconsistent with federal immigration law. Nor, to my knowledge, has Arizona authorized any enforcement mechanisms that violate other federal law.

The Justice Department's theory is, instead, that the Arizona law is unconstitutional because the government has preempted the field of immigration. Under the "field preemption" theory, a state law can, under certain circumstances, be preempted even if it is not inconsistent with federal law.

The power to regulate immigration has been held to be exclusively federal power. But the Supreme Court has also made it clear that not every state enactment that deals with aliens is a regulation of immigration and thus per se pre-empted. In De Canas v. Bica, 424 U.S. 351 (1976), the Court upheld an attempt by California "to strengthen its economy by adopting federal standards in imposing criminal sanctions against state employers who knowingly employ aliens who have no federal right to employment within the country." Here, as I understand it, Arizona similarly attempts to vindicate important state interests - including protecting the safety of Arizona residents - by adopting and enforcing federal standards.

To be sure, a state cannot enact legislation that "stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress." Hines v. Davidowitz, 312 U.S. 52 (1941). However, it's difficult to see how the Arizona law stands as such an obstacle.