The Department of Justice may challenge a new Arizona immigration law in court, Homeland Security Secretary Janet Napolitano said on Tuesday.
The bill would allow law enforcement officers who come into legal contact with individuals to demand proof of legal status if there is a "reasonable suspicion" they might be in the country illegally.
"The Department of Justice is looking at a potential legal challenge and looking at what the kinds of challenges could be," Naplitano told MSNBC's Andrea Mitchell.
She added: "I think it is a very difficult bill to enforce in a racially neutral way."
Critics of the law have argued that it will result in racial profiling. The law will take effect in 90 days if a court does not grant an injunction.