The U.S. Supreme Court takes up yet another incendiary election issue Wednesday when it hears arguments on a controversial Arizona law that targets illegal immigrants.

As with last month's test of the Obama health care overhaul, the case pits the federal government's assertion of power against some states, and with some exceptions, it pits Democrats against Republicans.

The Arizona law before the court, known as SB 1070, has become a model for other states, particularly those dominated by Republicans. Last year, however, a federal appeals court blocked enforcement of key provisions as an unconstitutional encroachment on federal immigration authority.

Historically, the federal government has the power to regulate immigration questions, while the states have the power to police illegal activities that threaten health and safety within their own borders. This case pits these two legal concepts against each other.

In recent years, Arizona has become the eye of the political storm over immigration. The state, which shares a 370-mile border with Mexico, contends that it bears a "disproportionate burden" of illegal immigration, due in large part to what it calls "lax enforcement" by the federal government.

Its brief paints a grim and frightening picture of life in the state: human traffickers more heavily armed than border patrol agents; Mexican drug cartels penetrating as far as 80 miles beyond the border, threatening police, invading homes and kidnapping people. Indeed, the situation is so bad, the state says, that large tracts of desert designated as national parkland have signs posted warning visitors that the area is an "active drug and human smuggling area" where they may "encounter armed criminals."

Arizona's Republican Gov. Jan Brewer alluded to these dangers when she signed the law in April 2010.

"We cannot sacrifice our safety to the murderous greed of drug cartels," she said. "We in Arizona have been more than patient waiting for Washington to act. But decades of federal inaction and misguided policy have created a dangerous and unacceptable situation."

Cooperation Or Conflict?

In response, the Obama administration notes that the federal government has increased the number of border agents by 40 percent in Arizona over the past five years, supplemented with 40 air-interdiction aircraft and 306 miles of new border fence.

Indeed, Arizona's critics point out that even as the state was passing its tough new law, illegal border crossings in the state were down dramatically, to numbers not seen since the 1970s.

Four specific provisions of the Arizona law are before the Supreme Court Wednesday. The state defends all of them as written to mirror, not supplant, federal law.

The most notable are the so-called show-me-your-papers provisions. One authorizes warrantless arrests when an officer has probable cause to believe someone is illegally in the country. Another requires state and local law enforcement officers, upon reasonable suspicion, to detain anyone stopped or arrested for any reason, no matter how minor, until the immigration status of that person is determined.

Paul Clement, who represents the state, contends such stops are an example of cooperation, not conflict, between federal and state authorities. Arizona's law "is consciously designed to complement the federal law and not replace it," he says.

But James Ziglar, who served as head of the immigration service during President George W. Bush's administration, disagrees, saying that instead of cooperating, Arizona is "confronting the federal system" by forcing into the federal process everybody who's even technically in illegal status. The Arizona law will "flood" the system, he says, so that the federal government will be unable to effectively enforce the current laws.

Indeed, the federal government says flatly that there is no way to have 100 percent enforcement of the federal immigration laws because there just aren't enough resources to hold everyone suspected of being in the country illegally and provide hearings for them.

As a result, the federal government has established priorities to deal first with dangerous criminals, felons, suspected terrorists and the like. It would be impossible to carry out those priorities, the government says, if the system is glutted with requests for information on every minor traffic offender who is suspected for some reason of being in the country illegally.

Who's An Illegal Immigrant?

Furthermore, Ziglar, the former Bush immigration enforcement chief, says that the immigration data system does not fully reflect the real status of many people. For instance, prosecutors often allow witnesses to stay in the country if they are the victims of violent crime, or if their testimony is needed to bust drug or human-trafficking rings. Also, the government uses its discretion to refuse deportation of refugees from certain countries — for example, Syria right now, or China at the time of Tiananmen Square. Nor does it deport people while they are seeking asylum from persecution abroad.

Individuals seeking asylum have no proof of legality until final approval is granted, according to Cecillia Wang, director of the ACLU's Immigrants' Rights Project. "If the Arizona police officer called the federal authorities to find out the status of the person, they would receive a response that the person is in removal proceedings," she says.

Arizona's Clement replies that whatever the problems, federal law mandates responsiveness and provides for a federal center that is manned 24 hours a day to do that. "Congress has been incredibly specific that the federal government shall respond whenever the state and local governments ask for that kind of information," he says.

Former state Sen. Russell Pearce, who sponsored Arizona's law, adds that the whole purpose of the law is what the statute refers to as "enforcement through attrition." Put another way, if the going gets tough enough for illegal immigrants, they will leave — as Pearce puts it, "self-deport." Pearce also accuses the federal government of bad faith.

"They love to tell lies, to tell people, 'Oh, we just can't do that,' " Pearce asserts. But when "you enforce the law, things start changing. It's just like Disneyland. You want the crowd to go home, you've got to turn off the lights."

Wang, however, says that Arizona legislators are wrong in thinking "there's an on/off switch — you're either legal or you're illegal." In fact, she says, "the system Congress has created really accounts for what actually happens in the real world," and in the real world, the immigration status of noncitizens is often "complex and fluid."

Concerns About Profiling

Even some law enforcement officers in Arizona worry that the state's new law will lead to racial profiling, since it provides stiff civil fines of up to $5,000 a day levied against law enforcement officers who fail to detain suspected illegal immigrants.

Clarence Dupnik, the sheriff of Pima County, which includes Tucson, says SB 1070 "coerces us to profile people, and we're going to get sued on both sides — one from the people that don't think we're enforcing the law and one from the people that say they're being profiled."

While Arizona's law has been blocked so far by the federal courts, a similar law in Alabama has gone into effect and has led to some embarrassing incidents, like the arrest of a German Mercedes executive when he couldn't produce proof that he was legally in the country during a routine traffic stop.

In Arizona, though the law is in legal limbo, some residents say they already feel its effects. Jim Shee, a 72-year-old U.S.-born citizen of Hispanic and Chinese descent, says that in the past year and a half, he has been stopped twice by police and asked for his papers. The first time, he says, he was questioned while he was sitting in his car at the side of the road, having pulled over so he could respond to a text message, and the second time, the officer told him it was because his window tinting was too dark.

"We're old folks driving a car, not speeding or anything like that, but here we are subject to 15 minutes of interrogation," he says. "I'm an American citizen and I am being stopped because of the color of my skin, what I look like." Shee, a retired exporter, says he now carries his passport with him.

Wider Consequences

The justices won't be deciding the case on evidence such as Shee's, however. That's because the case is a "facial challenge," meaning the government contends that even before the law goes into effect, the provisions in question are, on their face, unconstitutional in all applications. That makes this a particularly difficult case for the Obama administration to win.

In addition to the show-me-your-papers provisions at issue in Wednesday's case, there are two other provisions that may be on somewhat shakier ground at this stage. One makes it a state crime, punishable by a mandatory jail sentence, for an immigrant to fail to register under federal law. Another provision makes it a state crime for illegal immigrants to work or seek work. Currently, federal law makes it a crime for businesses to hire illegal immigrants, and for workers to use false documents, but federal law does not make it a crime for the employees to work. The state contends that it is thus free to legislate against workers because the federal law is silent on the subject. But the administration counters that state law unconstitutionally interferes with Congress' decision not to make working, by itself, a crime.

The federal government also argues that allowing 50 states to set their own immigration policies, many of which would be inconsistent with each other, would create exactly the kind of patchwork of immigration laws that the founding fathers sought to avoid in giving the federal government regulatory authority over immigration. Such a patchwork, the government contends, would make it difficult to do business in the U.S. and could create "significant foreign-policy consequences" as well.

Indeed, after Arizona passed SB 1070, countries throughout Central and South America issued statements criticizing the law, and two, El Salvador and Mexico, issued travel warnings to their citizens traveling to the U.S.

Clement, however, responds that under the U.S. system of government, just because a state law may cause foreign policy problems doesn't mean it is unconstitutional. He observes that when he was solicitor general in the Bush administration, the Supreme Court sided with Texas in a death penalty case, citing the state's sovereign right to administer its own criminal justice system, even though the state had clearly violated the Vienna Convention, a treaty signed by the United States, which requires foreign consulates to be notified whenever their country's citizens are imprisoned.

An Eight-Justice Court

A huge and varied array of individuals and organizations has filed briefs in the Arizona case. Supporting Arizona's position are 16 states, 56 Republican members of Congress, two Arizona sheriffs and some two dozen conservative organizations.

Opposing Arizona's position are 11 states; 12 countries; 68 Democratic members of Congress; three Arizona sheriffs; top State Department and national security officials from the Reagan, George W. Bush and Clinton administrations; and more than 150 civil rights, civil liberties and religious organizations, including the U.S. Conference of Catholic Bishops.

On Wednesday, only eight justices will be on the bench. Justice Elena Kagan has recused herself, as she did last year in another Arizona immigration case. She has not given a reason but presumably stepped aside because prior to her Supreme Court appointment, she served as solicitor general in the Obama administration and was involved in discussions about both cases.

An eight-justice court raises the possibility of a tie vote. If that were to happen, the lower court's decision would stand, meaning that much of the Arizona law would be invalidated, at least until a full nine-justice court could rule on a similar law in another case.

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