United States v Arizona: The federal suit on immigration
The US Justice Department, together with Homeland Security and the State Department, is suing the State of Arizona to void the controversial SB 1070 on undocumented immigrants. The basic grounds for the suit are that the Arizona law is unconstitutional under the supremacy and commerce clauses of the Constitution. Immigration is pre-empted by the federal government, and states cannot enact its own laws that go beyond the federal laws or impede their enforcement. It creates practical difficulties in enforcing the nation's immigration laws by diverting too many resources toward pursuing those whose only offence is being in the country without permission.
The Justice Department also argues, tangentially, that the law impacts negatively on foreign policy and the civil rights of citizens and non-citizens. For more information on the suit, see this useful Q&A from the Arizona Republic.
The federal case is not linked to the suits already being pursued in federal court by non-government immigrant advocates, but it does join them in asking for an injunction to stay the execution of the Arizona law till the challenges can be heard. This is because the Justice Department is not arguing on civil rights grounds--i.e., against profiling. Since that charge is speculative, the suit is brought on more constitutional grounds. The Justice Department is casting its net wide to get at all the local and state laws that were springing up even before Arizona. It is party to the challenge next session before the Supreme Court against Arizona's employer sanction law (see New York Times).
Proponents of the Arizona law feel the law will stand the challenge. But that might be wishful thinking. If the courts block implementation by the end of the month and later the Supreme Court knocks down the sanction law, the ballgame may well be over.
Much of the cry from the proponents has been that the law is popular and that the feds are wasting money that could be better spent to secure the border, which sounds like an argument that recognizes that their cause is in trouble.