Faced with mounting frustration over lack of federal enforcement of immigration laws, in recent years many states have passed measures intended to crack down on illegal immigration within their borders. These laws, in turn, have been challenged as impermissibly encroaching on a core federal function. Last week, the U.S. Supreme Court gave a major victory to proponents of these state measures, upholding key provisions of an Arizona law intended to punish companies for hiring illegal immigrants.

The Arizona law provides that state licenses to do business in that state can be suspended or revoked if a company knowingly or intentionally employs unauthorized aliens. The law also requires all Arizona employers to use the federal E-Verify system to confirm that workers employed are authorized to work in the U.S. In Chamber of Commerce v. Whiting, the Court was asked to determine whether these measures are preempted by federal immigration laws.

In a 5-3 decision, the Court upheld the Arizona law. Although the federal government controls immigration, states have remaining police powers. Federal immigration laws specifically reserve to the states licensing laws that may touch on workers' legal status. The Arizona law was specifically crafted to parallel and not conflict with federal immigration enforcement powers.

In terms of E-Verify, the Court stated that the federal government made the decision to make the system available for use by any state or private employer. Nothing in federal law prohibits states from requiring this option as the means for verification of an employee's legal work status.

Arizona's law is very similar to South Carolina's immigration statute. This decision probably dooms similar challenges to the legality of South Carolina's program, and may encourage more states to both impose sanctions for employment of illegal aliens, and expand the mandatory use of E-Verify.