Supporters of the nation's toughest crackdown on illegal immigration, on the verge of approval in the Arizona Legislature, say the state law is necessary to help stamp out crime and keep citizens and law enforcement officers safe.
The measure would make it a crime under state law to be in the country illegally. It would also require local police officers to question people about their immigration status if there is reason to suspect they are here illegally.
Immigrants unable to produce documents showing they are allowed to be in the U.S. could be arrested, jailed for up to six months, and fined $2,500.
"No longer will we sit by and let our citizens be killed, maimed, injured (and) hurt," said Republican state Sen. Russell Pearce, who sponsored the measure.
But civil rights activists warn that Arizona is inviting rampant racial profiling and police-state tactics.
"That is an unprecedented expansion of police power," said Alessandra Soler Meetze, executive director of the American Civil Liberties Union of Arizona. "It's giving police officers a green light to harass anyone who looks or sounds foreign."
The ACLU and immigrant rights groups are demanding Republican Gov. Jan Brewer veto the measure if it reaches her. The Republican has not announced whether she will sign it, but said she is a strong supporter of pragmatic immigration laws.
Her predecessor, Janet Napolitano, a Democrat who is now President Barack Obama's Homeland Security secretary, vetoed similar proposals.
The argument over the putative immigration bill played out Thursday as dozens of immigration agents raided a Phoenix shuttle bus operation that advertised van shuttle service from several cities in northern Mexico to cities in Arizona, New Mexico, California, Nevada, Oregon and Washington.
A second shuttle service a block away was also apparently raided by agents from Immigration Customs Enforcement.
ICE agents and Phoenix police were stationed outside the businesses.
An ICE spokeswoman would only tell The Associated Press the raids were part of an "ongoing investigation into allegations of human smuggling."
A phone call to Sergio's Shuttle was not answered Thursday morning.
Agents conducting the raid were dressed in black, some wearing hoods over their faces.
Current law in Arizona and most states doesn't require police to ask about the immigration status of those they encounter. And many police departments prohibit officers from inquiring out of fear that immigrants won't cooperate in other investigations.
The law also would crack down on employment for illegal immigrants by prohibiting people from blocking traffic when they seek or offer day labor on street corners. Also, a judge could fine a city for not enforcing the immigration law vigorously enough.
The new measure would be just the latest crackdown of its kind in Arizona, which has an estimated 460,000 illegal immigrants.
Pearce, the bill's sponsor, has been the driving force behind Arizona's tough new measures, including a law copied in other states that punishes companies caught knowingly hiring illegal immigrants. He insists the measures are aimed at enforcing immigration laws, not racial profiling.
"I believe handcuffs are a great tool, but you have to put them on the right people," said Pearce, a former cop who can list the local officers killed or wounded by illegal immigrants. "Get them off the police officers and put them on the bad guys."
Supporters of the crackdown also point to Phoenix's high kidnapping rate, which law enforcement says is fueled by immigrant and drug smugglers who snatch their rivals or their family members as a way to collect unpaid debts, make quick money or as retaliation for earlier abductions.
Anger over the porous Mexican border mounted last month when an Arizona cattle rancher was shot to death. Investigators said he may have been killed by drug runners working for cartels based in Mexico.
The new measure is supported by police unions representing rank-and-file officers, who deny they would engage in profiling.
It is opposed by police chiefs, who worry that the law would be too costly, that it would distract them from dealing with more serious problems, and that it would sow such distrust among immigrants that they would not cooperate with officers investigating other crimes.
Legal immigrants fear the law would give officers easy excuses to stop them, and that even U.S. citizens could find themselves detained if they can't prove their legal status.
"When they come up with these things, it doesn't matter if I'm here legally," said Jose Melendez, a 55-year-old naturalized U.S. citizen from Guadalajara, Mexico. "If they see a Mexican face and a Mexican name, they'll ask for papers."
Anti-immigration activists say the larger goal is to discourage illegal immigration by making the U.S. inhospitable.
"Most illegals would leave on their own if they felt the U.S. was serious about our laws," said William Gheen, president of Americans for Legal Immigration Political Action Committee.
House Republicans passed the bill on a party-line vote Tuesday. The Senate approved it in February but must vote on changes made in the House before sending it to the governor.