A federal judge in Arizona on Wednesday broadly vindicated the Obama administration's high-stakes move to challenge that state's tough immigration law and to assert the primary authority of the federal government over state lawmakers in immigration matters.

The ruling by Judge Susan R. Bolton, in a lawsuit against Arizona brought on July 6 by the Justice Department, blocked central provisions of the law from taking effect while she finishes hearing the case.

But in taking the forceful step of holding up a statute even before it was put into practice, Judge Bolton previewed her opinions on the case, indicating that the federal government was likely to win in the end on the main points.

The decision by Attorney General Eric H. Holder Jr. to throw the federal government's weight against Arizona, on an issue that has aroused passions among state residents, has irritated many state governors, and nine states filed papers supporting Arizona in the court case.

But Judge Bolton found that the law was on the side of the Justice Department in its argument that many provisions of the Arizona statute would interfere with federal law and policy.

Gov. Jan Brewer said the state would appeal the decision.

Although Judge Bolton's ruling is not final, it seems likely to halt, at least temporarily, an expanding movement by states to combat illegal immigration by making it a state crime to be an immigrant without legal documents and by imposing new requirements on state and local police officers to enforce immigration law.

"This is a warning to any other jurisdiction" considering a similar law, said Thomas A. Saenz, president of the Mexican American Legal Defense and Educational Fund , which brought a separate suit against the law that is also before Judge Bolton.

The Arizona law stood out from hundreds of statutes adopted by states in recent years to discourage illegal immigrants. The statute makes it a state crime for immigrants to fail to carry documents proving their legal status, and it requires state police officers to determine the immigration status of anyone they detain for another reason, if there is a "reasonable suspicion" the person is an illegal immigrant.

The mere fact of being present without legal immigration status is a civil violation under federal law, but not a crime.

Arizona's lawyers contended that the statute was written to complement federal laws. Judge Bolton rejected that argument, finding that four of its major provisions interfered or directly conflicted with federal laws.

The Arizona police, she wrote, would have to question every person they detained about immigration status, generating a flood of requests to the federal immigration authorities for confirmations. The number of requests "is likely to impermissibly burden federal resources and redirect federal agencies away from priorities they have established," she wrote.

While opponents of the Arizona law had said it would lead to racial profiling, the Justice Department did not dwell on those issues in its court filings. But Judge Bolton brought them forward, finding significant risks for legal immigrants and perhaps American citizens. There is a "substantial likelihood that officers will wrongfully arrest legal resident aliens," she wrote, warning that foreign tourists could also be wrongly detained.

The law, she found, would increase "the intrusion of police presence into the lives of legally present aliens (and even United States citizens), who will necessarily be swept up" by it. Judge Bolton was appointed by President Bill Clinton in 2000.

Hannah August, a spokeswoman for the Justice Department, said, "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."

Some critics said Judge Bolton had decided too quickly. Peter Schuck, a professor of immigration law at Yale, said Judge Bolton should have allowed the law to go into effect, which it was scheduled to do on Thursday, before issuing an order that curbed the power of a state legislature.

"She rushed to judgment in a way I can only assume reflects a lot of pressure from the federal government to get this case resolved quickly," he said.

Now Judge Bolton's ruling has shifted the political pressure back onto President Obama to show that he can effectively enforce the border, and to move forward with an overhaul of the immigration laws, so that states will not seek to step in as Arizona did.