PHOENIX — Arizona’s frustrations over federal enforcement of the state’s border with Mexico spawned a movement nearly a decade ago to have local police confront illegal immigration. Now, the state’s experiment in immigration enforcement is falling apart in the courts.

A ruling Friday that struck down the state’s 2005 immigrant smuggling law marks the latest in a string of restrictions placed by the courts on Arizona’s effort to get local police to take action on illegal immigration. The smuggling law, like similar state statutes, was tossed because a judge concluded it conflicted with the federal government’s immigration powers.

“There may be some broad sympathy within a constituency for these laws, but that constituency isn’t enough to overcome the problems those laws pose,” Peter Spiro, a Temple University law professor who specializes in immigration law.

For years in Arizona, many officials resisted suggestions that local and state police agencies confront illegal immigration, long considered the sole province of the federal government. But the notion gained political traction as voters grew frustrated over the state’s status as the nation’s then-busiest immigrant smuggling hub and over what critics said was inadequate border protection by Washington.

A small number of the state’s immigration laws have been upheld, including a key section of Arizona’s landmark 2010 immigration enforcement law that requires police to check people’s immigration status under certain circumstances.

But the courts have slowly dismantled other Arizona laws and policies.

U.S. District Judge Susan Bolton on Friday threw out the smuggling law as part of the Obama administration’s challenge of the state’s 2010 immigration law, which made a minor change to the 2005 statute. The dispute over the smuggling law is all that remains of the administration’s challenge of the 2010 law.

Gov. Jan Brewer’s office, the chief defender of the 2010 law, didn’t immediately respond to messages left Saturday.

Jonathan Paton, a former Republican lawmaker from Tucson who was one of the smuggling law’s top sponsors, said the Obama administration’s efforts to overturn the smuggling statute is evidence that Washington doesn’t care about Arizona’s problems.

“It basically shows this administration has no intention to enforce its own laws or let the state enforce its laws,” Paton said.

The U.S. Justice Department, which pressed the challenge on behalf of the Obama administration, issued a statement saying it was pleased with Friday’s ruling.

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