PHOENIX, Arizona (CNN) -- A federal judge has blocked one of the most controversial sections of a tough Arizona immigration law, granting a preliminary injunction Wednesday that prevents police from questioning people about their immigration status.
That provision of the law requires police to "make a reasonable attempt to determine the immigration status of a person stopped, detained or arrested" if the officer has a reasonable suspicion that the person is in the United States illegally.
U.S. District Judge Susan Bolton's ruling, in response to a motion filed by the federal government, came with scant hours to go before the law goes into effect.
She also blocked provisions of the law making it a crime to fail to apply for or carry alien registration papers or "for an unauthorized alien to solicit, apply for, or perform work," and a provision "authorizing the warrantless arrest of a person" if there is reason to believe that person might be subject to deportation.
Seven lawsuits are seeking to block implementation of the law, signed by Arizona Gov. Jan Brewer in April. The law, which also targets those who hire illegal immigrant laborers or knowingly transport them, is to go into effect Thursday.
CNN senior analyst Jeffrey Toobin said the ruling reflects the government's argument that immigration enforcement should be dealt with at the federal level.
"Arizona may have good intentions, they may be trying to make up for where the us government has failed, but what the judge is saying is this is not the way to do it."
"I think this a case very much destined for the Supreme Court," as other states pass similar laws, Toobin said.
The Court of Appeals could take up the case in a matter of days, but the earliest the Supreme Court could look at it would be October because the high court is in summer recess.
Arizona Gov. Jan Brewer said she was disappointed by the ruling and that Arizona will file an expedited appeal to the 9th Circuit Court of Appeals.
"This fight is far from over. In fact, it is just the beginning, and at the end of what is certain to be a long legal struggle, Arizona will prevail in its right to protect our citizens," she said in a statement. "I am deeply grateful for the overwhelming support we have received from across our nation in our efforts to defend against the failures of the federal government."
She emphasized that Wednesday's action was a temporary injunction, and that many other parts of the bill will go into effect as planned.
For instance, a ban on so-called sanctuary cities stands, as does making it a crime to pick up day laborers who are illegal immigrants. The parts of the law dealing with sanctions for the hiring of illegal immigrants also goes into effect Thursday.
Another supporter of the law, Maricopa County Sheriff Joe Arpaio, said that he and his crusade against illegal immigration will not be deterred.
" I am not really dissapointed about the judges decision," Arpaio said. "I know what my policies are and we are going to continue doing what we have been doing."
The Center for Immigration Studies, which advocates immigration reduction, was disappointed but not surprised by the ruling, said executive director Mark Krikorian.
"If the opponents hadn't turned it into this bogey man it would have been a useful, if modest, tool for the police," said Krikorian.
He argues the Arizona law wasn't intended to usurp federal authority.
"Arizona does not have its own immigration policy, even with the law. They are buttressing federal law," Krikorian said.
President Barack Obama, a critic of the Arizona law, was not expected to comment on the ruling Wednesday.
The Justice Department issued a statement saying the court "ruled correctly."
"While we understand the frustration of Arizonans with the broken immigration system, a patchwork of state and local policies would seriously disrupt federal immigration enforcement and would ultimately be counterproductive," the statement said. "States can and do play a role in cooperating with the federal government in its enforcement of the immigration laws, but they must do so within our constitutional framework."
The Department of Homeland Security also weighed in, saying that the injunction "affirms the federal government's responsibilities in enforcing our nation's immigration laws."
Meanwhile, the president of the Mexican American Legal Defense and Educational Fund, Thomas A. Saenz, said, "I think it's a great victory for the Constitution. I think all the provisions she has blocked from implementation were the most egregious."
Reaction was not limited to the United States.
Applause erupted at a protest outside the U.S. embassy in Mexico City when a speaker announced the judge's decision.
"I think it is a big victory, and it is the start of many more," said Sergio de Alba, president of the National Confederation of Workers and Farmers Organizations.
Minutes earlier, he had called on Mexicans to boycott products from the United States in protest.
Protesters attached signs to a gate in front of the embassy, with one slogan saying, "Boycott Against Arizona-Nazizona, home of hunting migrants and the Ku Klux Klan."
Opponents say the law will lead to racial profiling, which is illegal.
Supporters point out that the law prohibits racial profiling and people cannot be stopped and asked for proof of legal residence based solely on their looks.
In addition to the U.S. Justice Department, the American Civil Liberties Union, the National Coalition of Latino Clergy, the Christian Leaders League of United Latin American Citizens and other individuals or groups have asked the judge to halt the law, commonly known as SB 1070. Bolton heard arguments in the case last week from the Justice Department and the ACLU.
The separate hearings were held in Phoenix, where Bolton sits on the U.S. District Court for the District of Arizona.
Bolton's courtroom was packed during the two July 22 hearings and protesters chanted outside throughout the afternoon.
Seven protesters were arrested on civil disobedience charges, according to the National Day Laborer Organizing Network.
The legal arguments revolved around a range of issues, including racial profiling, effective enforcement and possible harm to Arizona's citizens.
Attorneys from the Obama administration presented their case at the second hearing. The administration's challenge contends Arizona's law would usurp federal supremacy on immigration.
Brewer attended the hearing.
Arizona has argued that the federal government has not done a good job of securing the border.
"A law unenforced is no law at all," said state attorney John Bouma.
The American Civil Liberties Union and a coalition of civil rights groups argued earlier in the day that the controversial law amounts to racial profiling and will have a profound effect if it goes into effect.
"It treats people of color as suspects first, rather than citizens," attorney Karen Tumlin said after the hearing.
Bouma said the law would not treat people unfairly.
"These are hypothetical arguments. Local police are enforcing immigration laws all over the country," he told Bolton.
Those in favor of the law say SB 1070 is consistent with federal law. They say the law explicitly prohibits racial profiling and they are challenging the legal standing of many of the groups opposed.
They also contend opponents of the law have not been able to show there will be any harm from its implementation.
During the first hearing, Bolton said the law has a section allowing parts to still take effect even if other parts are struck down, according to CNN affiliate KNXV.
Tumlin, managing attorney for the National Immigration Law Center, and other lawyers and foes of SB 1070 repeated assertions that Arizona's law should be rejected.
"We are here to defend the rights of those who cannot stand up for themselves," said Terri Leon, CEO of the Friendly House, which supports the legal challenge by the American Civil Liberties Union.
Bolton heard a challenge to SB 1070 by an Arizona police officer the previous week.
-- CNN's Catherine Shoichet, Phil Gast, Adam Blank, Holly Yan and Arthur Brice contributed to this report.
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