Arizona has decided that if the federal government will not live up to its responsibility to control the border, it will. Gov. Jan Brewer, a Republican, signed a bill that allows police officers to inquire about a person's immigration status if there is reason to suspect that individual might be an illegal immigrant. The governor correctly noted that the new law "represents another tool for our state to use as we work to solve a crisis we did not create and the federal government has refused to fix."

The latest example of that failure is the Obama administration's refusal to finish the border fence begun with some reluctance by the Bush administration.

Critics of the new law, who plan a court challenge, ask how police officers will "know" by observation whether someone might be in the country illegally. Police officers regularly make judgment calls about suspicious behavior, whether it involves erratic driving, passing small packets on the street in drug-infested neighborhoods, or searching cars for drugs and alcohol. "Immigrant groups" are upset that in Arizona people might actually be forced to comply with the law or face deportation.

Let's get something straight. The failure to protect America's southern border has been a bipartisan effort. Democrats want more illegal immigrants in the country because they are a potential source of votes they hope will contribute to a permanent Democratic majority. Republicans and their donors want more illegal immigrants in America because they are a source of cheap labor. Once you understand this, you can ignore much of the talk about "human rights."

If a state, or nation, has laws it will not enforce for political reasons, it mocks both the law and politics, to say nothing of the cultural order. If the language of laws has no meaning other than what lawmakers assign to them after a law is enacted, it is proof that we have arrived in a kind of legal "Wonderland" in which Alice is told by Humpty Dumpty, "When I use a word ... it means just what I choose it to mean - neither more nor less." To which Alice responds, "The question is ... whether you can make words mean so many different things." Politicians constantly try.

So what does the "illegal" in illegal immigration mean? For that matter, what does the less judgmental and legally vacuous "undocumented alien" mean? If something is illegal, according to dictionary.com, it is "forbidden by law or statute." If one is "undocumented" that person lacks "the needed documents, as for permission to live or work in a foreign country." Sociological and political considerations notwithstanding, the law should be the law and its requirements ought to be universally adhered to, or punishment imposed for their violation.

According to the Federation for American Immigration Reform, as of 2007, there are about 475,000 illegal immigrants in Arizona straining an already overburdened economy. Taxpaying citizens must underwrite the cost of schooling for their children, as well as visits to emergency rooms. In California, several hospitals have had to close because they could no longer afford to give free care to noncitizens. Gangs in Arizona operate under the command of drug lords in Mexico. This and other criminal activity threaten the peace and security of Arizonans and potentially all American citizens. Is this something that must be endured for the sake of "human rights groups" and "immigration rights groups," or is it long past time to slow the flow?

The Arizona legislature and Gov. Brewer have correctly chosen to slow the flow. They realize a state and a nation unwilling to protect their borders cannot hope to preserve qualities that have made this country what it is but won't be for much longer if we permit this illegal invasion to continue.

Cal Thomas is the country's most widely syndicated columnist.