Doocy: “Some say” the “federal government is overstepping its authority” in challenging AZ immigration law. From the July 13 edition of Fox News' Fox & Friends:

DOOCY: Despite strong opposition from lawmakers and voters across the country, the Department of Justice refuses to back down from its lawsuit against Arizona. It's just the latest example of what some say is a federal government that is overstepping its authority and getting too big. But how can states limit the government's power? The federal government.

However, Bush administration challenged Illinois immigration law

Bush administration sued Illinois, seeking to have immigration statute ruled unconstitutional. In September 2007, the Bush administration sued the state of Illinois, seeking to have an Illinois immigration statute declared unconstitutional under the Supremacy Clause of the U.S. Constitution. The Illinois statute was intended to prevent businesses from using an E-Verify program over concerns about the program's speed and accuracy. The Los Angeles Times reported:

Brought by the Justice Department on behalf of the Department of Homeland Security, the civil suit is intended to preempt an Illinois state law that bars businesses from using the employee verification program until its databases are faster and more accurate. The suit is also intended to send a clear message to other states and cities about the way they handle immigration enforcement. ... Advocates cited the Illinois lawsuit as yet another blow to immigrants -- along with an increase in work-site raids and high-profile deportations -- in the aftermath of the Senate's failure to pass a comprehensive immigration law.

Fox News has omitted this fact in past criticism of the AZ lawsuit. As Media Matters has noted, while criticizing the Justice Department's lawsuit against Arizona over the state's controversial immigration law, Fox “straight news” anchor Martha MacCallum claimed that she and Fox News' “brain room” couldn't find "[a]nother case where the federal government sued a state," despite the fact that Fox had covered the Illinois lawsuit at the time.

Also, legal experts -- and even Fox's Napolitano -- agree DOJ will succeed, Arizona law is “unconstitutional”

Fox News' own Judge Napolitano: Arizona law “is unconstitutional” because AZ “can't write a law that says the federal law means something different in Arizona than it does in the other 49 states.” On the July 7 edition of Fox Business Network's Varney & Co., Fox legal analyst Judge Andrew Napolitano railed against the Arizona law, calling it “un-American.” Napolitano called the law “unconstitutional” and noted that the Supreme Court has ruled that immigration laws are “strictly a federal issue.” From Varney & Co.:

Because the Supreme Court has held that when the states formed the federal government they truly gave away their power to have relations with foreign countries and with foreigners including immigration. Directly on point a Pennsylvania case in which the state of Pennsylvania sought to find Nazi sympathizers which is pre-World War II amongst its aliens so it ordered all aliens to register with the state of Pennsylvania. The Supreme Court said you have nothing to do with aliens. It is strictly a federal issue.

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[Arizona] can't do that. It can't write a law that says the federal law means something different in Arizona than it does in the other 49 states.

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If I fall asleep in the sun at a resort in Scottsdale and I haven't shaved in three days and I go jogging, they may stop me. And I will have no proof of my papers on me and they will arrest me because I can't prove who I am. That is un-American. That is unconstitutional. That's what will happen.

Constitutional law expert Chemerinsky: Arizona law is unconstitutional. On June 6, Yahoo! News reported that constitutional law expert Erwin Chemerinsky said “federal law clearly pre-empts the Arizona measure...rendering the state law unconstitutional.”

There's less debate over whether the Arizona law would hold up to a supremacy challenge. Erwin Chemerinsky, an expert in constitutional law and the dean of the law school at the University of California, Irvine, told Yahoo! News federal law clearly pre-empts the Arizona measure in his view, rendering the state law unconstitutional.

Constitutional law expert Dellinger: DOJ “had no choice but to bring this suit.” New Republic reported that constitutional law expert Walter Dellinger said the DoJ “had no choice but to bring this suit”:

Giving the national government control over immigration into the United States was a major decision made by the framers of the Constitution. That is neither a liberal nor a conservative position. Allowing states to set their own immigration policy could lead in the future to more rather than less unlawful immigration. Given the freedom of movement within the United States and the implications of immigration for domestic national issues and foreign policy, it is unthinkable to leave immigration policy to thirteen or fifty different states. Calibrating the right combination of enforcement tools to utilize is at the core of the national power over immigration, and state laws are preempted whether they purport to add to or subtract from the system put in place by Congress. Whether current federal enforcement is adequate or not, whether Arizona's law is wise or not, whether suing is good politics or not are all beside the point: it is essential that the federal government's control over immigration into the United States be protected from state interference. In my view the Justice Department had no choice but to bring this suit.

LA Times: “most legal experts predict” that Arizona's law “is likely to be struck down.” In a July 9 article titled “Arizona immigration law unlikely to survive federal lawsuit,” and subtitled “Legal experts cite the longstanding principle that the federal government has exclusive control over immigration,” the L.A. Times reported that “most legal experts predict” that the Arizona law “is likely to be struck down”:

Arizona's law giving local police immigration enforcement powers is likely to be struck down, most legal experts predict, now that the Obama administration has gone to court asserting that it conflicts with federal law.

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It's one thing for MALDEF [Mexican American Legal Defense and Educational Fund] or the ACLU to say this [Arizona law] interferes with federal policy. It is quite a different thing when the federal government goes to court and says it," said Jack Chin, a University of Arizona law professor. “The clear rule has been that states do not have the power to regulate immigration.”