A judge held two hearings Thursday, in a courtroom packed with top Arizona officials and spectators, on whether the state's new immigration law should take effect amid a flurry of legal challenges against the crackdown.

Arizona Gov. Jan Brewer attended the second hearing, which focused on the U.S. Justice Department requesting a preliminary injunction blocking key sections of the law from taking effect next week.

Judge Susan Bolton did not issue a ruling following the day's proceedings.

Opponents of Arizona's immigration law gather outside the Sandra Day O'Connor federal courthouse in Phoenix last week. (Matt York/Associated Press) During the morning hearing, Bolton told lawyers for the American Civil Liberties Union that she's required to consider blocking only parts of the law, not the entire statute as they had requested. She said the law has a section allowing parts to still take effect even if other parts are struck down.

ACLU attorney Omar Jadwat said the law's provisions are supposed to work together to achieve a goal of prodding illegal immigrants to leave the state. He called it unconstitutional and dangerous.

'All this hypothetical that we're going to go out and arrest everybody that's Hispanic .... That's impossible."— John Bouma, lawyer for Gov. Jan Brewer

Most of the controversy about the law centres on provisions related to stops and arrests of people, new crimes related to illegal immigrants, and a requirement that immigrants carry and produce their immigration papers.

Attorney John Bouma, who represents Brewer, said those challenging the law haven't demonstrated that anyone would suffer actual harm if it takes effect, and that facts — not conjecture — must be shown.

"In Arizona we have a tremendous Hispanic heritage," Bouma said. "To think that everybody that's Hispanic is going to be stopped and questioned … defies reality. All this hypothetical that we're going to go out and arrest everybody that's Hispanic, look around. That's impossible."

Defendants include various county officials from throughout the state, most of whom sent lawyers to the hearing.

'It's morally wrong'

Outside the courthouse, opponents gathered in prayer before the hearing started. They carried paper doves attached to plants representing olive branches, a symbol of peace.

Sarah Fox, a 64-year-old Phoenix nurse, said the new law takes the country's economic problems out on immigrants, who she believes are being used as a scapegoat.

"It's morally wrong," she said. "I'm getting old and I don't have many years left to speak out against what is wrong."

Supporters of the law waved signs, some reading "Illegal is illegal," and clutched American flags.

Debbi MacNicol, a 55-year-old Phoenix psychiatric nurse who carried a gun on her hip and wore a T-shirt that read "Don't Tread on Me," said she supports the law because she fears Mexico's drug war will spill over into Arizona.

The law requires officers, while enforcing other laws, to check a person's immigration status if there's a reasonable suspicion that the person is here illegally. It also bans people from blocking traffic when they seek or offer day-labour services on streets and prohibits illegal immigrants from soliciting work in public places.

Since Brewer signed the measure into law in April, it has inspired rallies in Arizona and elsewhere by advocates on both sides of the immigration debate.

U.S. Justice Department lawyers contend that local police shouldn't be allowed to enforce the law because, in part, it's disrupting the United States' relations with Mexico and other countries.