The Ninth U.S. Circuit Court of Appeals heard arguments Tuesday from the federal government about why another provision of Arizona's controversial immigration law should remain blocked.
The case is about whether Arizona can enforce a provision of its immigration law, SB 1070, that makes it state crime to harbor or transport immigrants in the country illegally.
A federal judge blocked that provision last year on the grounds that it conflicts with federal law.
Lawyers representing Arizona are asking the appeals court to reinstate it.
The challengers of the law are a coalition of civil rights group, but a lawyer from the U.S. Department of Justice joined them to argue against it.
According to the Associated Press, DOJ lawyer Mark Stern told the three-judge panel that the federal government is meant to enforce immigration laws, not states.
From the bench, Judge John Noonan criticized the confusing way Arizona's law was written, according to news reports.
The language of the statute begins, "It is unlawful for a person who is in violation of a criminal offense..."
"It's nonsense as it stands," said Noonan, according to the Associated Press. "How do you violate an offense?"