Just as has been the case for similar measures in other states, South Carolina's harsh new immigration law has been unable to withstand a challenge in the courts. From The New American:

A judge for the U.S. District Court for the District of South Carolina issued a preliminary
injunction on December 22 against key provisions of the South Carolina immigration statute. The plaintiffs in the  case include a group of civil rights organizations and the United States Department of Justice.

Of the 20 sections of the South Carolina law, four of them were challenged and are now blocked from
enforcement. These four include provisions which that state criminal sanctions for: “harboring and
transporting of unlawfully present persons”; “failure to carry alien registration materials”; “the
creation of fraudulent identification documents”; and the directive to state and local law
enforcement officials to “determine the immigration status of certain persons encountered in
routine traffic stops and other contacts in which there is a ‘reasonable suspicion’ that the person
may be in the United States unlawfully.”

The civil rights groups challenging the law argue that enforcement of the law requires de facto
racial profiling. The Justice Department argues that the Constitution places all power over the
establishment of immigration policy in the hands of the federal government and that the legislature
of South Carolina is thus preempted from passing legislation in that area of the law.

The argument is that once the feds have “occupied the field,” of this or that area of the law or policy, then no other government (state or local) may trespass therein.