The United States Court of Appeals for the Ninth Circuit has upheld a trial judge’s ruling blocking the most egregious parts of Arizona’s infamous immigration law. The three-judge panel said that Arizona intruded onto federal responsibility by requiring that police officers check the immigration status of anyone they have “reasonable suspicion” of being in the state without authorization, demanding that immigrants carry papers and making it a crime for illegal immigrants to work or look for work.

In a powerful concurring opinion, Judge John Noonan paid particular attention to the first section of the law, which enshrines the expulsion of illegal immigrants as official state policy. “That 50 individual states or one individual state should have a foreign policy is absurdity too gross to be entertained,” Judge Noonan said. “In matters affecting the intercourse of the federal nation with other nations, the federal nation must speak with one voice.”

Unfortunately, that voice has been muddled by the Obama administration. Even though the Justice Department sued to block the Arizona law as an unwarranted intrusion into federal power, the Department of Homeland Security under Secretary Janet Napolitano has been doggedly expanding efforts to enlist local help in deportations, ignoring local communities’ objections about racial-profiling and worries about civil rights violations.

We are encouraged that the Ninth Circuit explicitly rejected the pernicious idea, put forth by the Bush administration, that the states have the “inherent authority” to enforce civil provisions of immigration laws. They don’t.

Arizona’s immigration radicals, including Gov. Jan Brewer and State Senate President Russell Pearce, vowed to keep fighting. But they should read the decision and give it up. So should other states — like Florida, Georgia and Alabama — that are considering copycat bills.