It appears that the circus surrounding the Arizona immigration law has just taken a turn for the crazy: BBC World News reported yesterday that the government of Mexico filed an amicus curiae (“a friend of the court”) brief in US federal court, saying that “the law is unconstitutional and would damage bilateral relations.”

The Mexican government’s brief added that the law could lead to “unlawful discrimination against Mexican citizens”. Have they read the law? Have they analyzed case law? Do they know anything about the Constitution, or how the Constitution is interpreted? The bigger question, at least in my mind, is why Mexico feels that it has any business at all interpreting American law in the first place.

This wouldn’t be the first time the Mexican government under President Felipe Calderón has insulted the US and its sovereignty; while addressing a joint session of Congress, the Mexican president openly criticized the law, declaring that it “introduces a terrible idea that uses racial profiling as a basis for law enforcement.”

Of course, the White House agrees with this analysis (even though Attorney General Eric Holder had not actually read the law), and according to Secretary of State Hillary Clinton, plans to join a lawsuit to challenge the law in federal court. But can they win? Do they have a case?

By now, most legal experts have dismissed the “racial profiling” critique. The facts and the substance of the law simply do not support these claims – Like any search or seizure, Arizona law requires law enforcement to establish both “lawful contact” (they must have a reason to stop an individual and question them) and “reasonable suspicion” (they must have a legitimate reason to believe that the individual may be engaged in illegal activity). Both of these legal doctrines are guided by case law that carefully defines the limitations and abilities of law enforcement.

The most damning of evidence, however, is the fact that federal law does not demand either requisites; the 2005 Supreme Court case Mueller v. Mena basically says that law enforcement can ask an individual for identification and immigration papers for any reason whatsoever, regardless of whether or not they may suspect a crime is being committed. In this regard, federal law is stricter than Arizona’s law.

Other critics have cited the Supremacy Clause, which provides that federal law trumps state law. But this doesn’t make much sense, either. The most obvious criticism of this approach is the fact that the Supremacy Clause is meant as a guideline for state laws that are in conflict with federal law, not supportive of them. Pretend for a moment that Arizona did the opposite and made all illegal immigrants legal; this would conflict with federal law, and thus, the Supremacy Clause would override Arizona’s attempt. In the actual case, Arizona’s law is not as stringent as federal law, and only offers local support for existing federal policies. The Supremacy Clause has, historically, never been interpreted in this way.

Others, still, argue that the immigration law must be uniform, and that states cannot have differing immigration policies. But does this mean that sanctuary cities are illegal? It must, if one were to interpret the law in this manner. Opponents of the Arizona law should be careful what they wish for – they may find themselves dealing with a court-ordered end to sanctuary policies.

The hysteria over the law is a product of misunderstanding and outright distortions on behalf of the media, which has not adequately analyzed the substance of the law, and as a result, has fueled its opposition. Now, foreign governments are challenging American laws and the Constitution. Foreign officials are advising us of the legality of our own laws. And what does our President do? He agrees.

Tom Bortnyk is a columnist for the political blog Informed Dissent.