With the U.S. Supreme Court's decision last Monday to review Arizona's immigration law, the legitimacy of such state laws will finally be resolved. The decision, which will be issued by the end of the court's term in June, will doubtlessly affect states such as Alabama that have passed similar immigration laws designed to assist the federal government's detention and deportation of illegal immigrants.

Arizona's immigration law raised the ire of the Obama administration and led to its unprecedented lawsuit against the state. According to Eric Holder's Department of Justice, the most controversial provision is a requirement that police officers check the immigration status of individuals they arrest for other violations, if the officers have a reasonable suspicion the individuals are in the country illegally. This is identical to the provision in Alabama's new immigration law that the 11th U.S. Circuit Court of Appeals recently upheld. But the 9th U.S. Circuit Court of Appeals -- the nation's most reversed appeals court -- came to a different conclusion, upholding an injunction against implementation of Arizona's law.

The Obama administration claims this provision interferes with the federal government's enforcement (or, more accurately, nonenforcement) of U.S. immigration laws. But federal law specifically directs the federal government to "respond to an inquiry" by state and local government agencies "seeking to verify or ascertain the citizenship or immigration status of any individual." For years, Congress has funded the Law Enforcement Support Center administered by the Department of Homeland Security to provide immigrant status determinations to law enforcement officials 24 hours a day, seven days a week. The 287(g) program, another provision in federal law, also encourages states "to cooperate with the Attorney General in the identification, apprehension, detention, or removal of aliens not lawfully present in the United States."

Congress clearly wanted the states to help the feds enforce our immigration laws, and the laws passed by Arizona and Alabama do exactly that. They enhance the federal government's ability to find, detain and deport individuals who are illegally in the United States. That is why the 9th Circuit's decision enjoining Arizona's law made no sense. It was so illogical that the dissenting judge compared the majority's misinterpretation of federal law to Humpty Dumpty's claim in "Alice in Wonderland" that a word "means just what I choose it to mean."

What is so bizarre about this situation is that at the same time that the Justice Department is trying to stop local law enforcement officials from checking the immigration status of individuals they arrest, the State Department is doing everything it can to force local law enforcement officials to check the immigration status of anyone they arrest so that foreign nationals can be notified of their right to consult their country's diplomatic officials under applicable international treaties on consular access. And despite the administration's public claims that these laws would lead to racial profiling, the Justice Department has made no such claims in these lawsuits because both Alabama and Arizona's law strictly prohibit race or ethnicity from being considered by police officers.

Of course, one of the most effective means of discouraging illegal immigration -- implemented by both Arizona and Alabama -- will not be before the Supreme Court this term. Just like Alabama, Arizona passed a law in 2007 that forces employers to use the E-Verify system and sanctions employers with the possible loss of their business licenses if they knowingly hire illegal aliens. The Obama administration challenged that law as well. However, in a resounding defeat this past May, the Supreme Court upheld Arizona's employer law as constitutional. The inability to work is one of the key reasons that illegal immigrants have started self-deporting from Arizona and Alabama.

Given that the Supreme Court and other courts of appeal have recognized the inherent authority of local police officers to inquire into the immigration status of individuals who have been lawfully detained, it seems highly likely that the Obama Justice Department will lose its second immigration case against Arizona. And that will clear the way for other states to help the federal government enforce our immigration laws.

Hans A. von Spakovsky is a senior legal fellow at The Heritage Foundation.