Whether they are armed with bombs or bacteria, stopping weaponized individuals from harming others ─ intentionally or unintentionally ─ falls perfectly within the purview of the “night-watchman state of classical-liberal theory,” in the words of the philosopher Robert Nozick.

But thumping majorities within rarified libertarian, Objectivist and loony left circles disagree.

When Objectivists eulogized the dazzling Randian Madeleine Pelner Cosman, Ph.D., Esq., most downplayed her trenchant opposition to the unfettered flow of migrants across the 1,940-mile-long border with Mexico. To that end, the late Dr. Cosman “never hesitated to put her own time, money and neck on the line for her beliefs,” even volunteering as a patrolwoman with the San Diego County Sheriff’s Department.

The quintessential “Renaissance woman,” Dr. Cosman was an expert aviator, health-care policy analyst, marksman and musician. But on immigration, she sounded a bum note.

It is commonly accepted that to express a yen for America before mass, state-orchestrated migration is the mark of a xenophobe. Or, conversely, of a less-than dynamic dude or dame. In the libertarian universe of Virginia Postrel, to eschew cities as crowded as Calcutta is to reject rapid technological transformation and the division of labor (Cairo-style).

Margalit Fox of the New York Times, however, surprises. In her tribute, Ms. Fox remarked, perceptively, that it was Ms. Cosman’s “passion for what she called the ‘glorious order’ of the past that led her first to a career in medieval and Renaissance studies and more recently to wide public advocacy of tougher immigration laws.”

Less forgiving was Ms. Fox’s colleague, David Leonhardt, also of the NYT. Leonhardt made up for his colleague’s “lapse” by libeling the late Dr. Cosman as a “white supremacy sympathizer.”

Ms. Cosman’s study of “the effects of illegal immigration on the United States health-care system” culminated in the article “Illegal Aliens and American Medicine,” published, in 2005, by The Journal of American Physicians and Surgeons. It addressed the effects on the health system of the bleeding Southwestern border.

That Mexico is Swine Flu Ground Zero has thrown Dr. Cosman’s work into sharp relief.

Consider: To qualify for a lawful permanent residency green card, I was screened thoroughly for communicable diseases and a criminal record. The idea that the host population has no right to know whether this writer, a legal immigrant to the U.S., was carrying dread diseases is ludicrous; plain liberal lunacy.

Alas, such screening is reserved for a biased sample of the population: potential immigrants who’re law abiding, healthy and relatively well-off.

On the other hand, not only are illegal aliens never asked about their immigration status, they go unexamined for contagious diseases and are granted free health passes and free medical care in the event that they fall ill.

The influx of illegal aliens has serious hidden medical consequences, given that they often hail from backward and benighted regions, where “diseases that American medicine fought and vanquished long ago” still rage.

Tuberculosis had largely disappeared from America “thanks to excellent hygiene and powerful modern drugs.” But a new Multi-Drug Resistant Tuberculosis, endemic to Mexico, has crossed into the U.S. It kills 60 percent of those infected. “Each illegal with MDR-TB coughs and infects 10 to 30 people, who will not show symptoms immediately. Latent disease explodes later.”

Mulishly, the left has been savaging Michelle Malkin and Michael Savage for alerting to the consequences of not policing the border. However, epidemiological studies conducted by public health officials back the two arch-conservatives:

TB was virtually absent in Virginia until in 2002, when it spiked a 17 percent increase, but Prince William County, just south of Washington, D.C., had a much larger rise of 188 percent. Public health officials blamed immigrants. In 2001 the Indiana School of Medicine studied an outbreak of MDR-TB and traced it to Mexican illegal aliens. The Queens, New York, health department attributed 81 percent of new TB cases in 2001 to immigrants. The Centers for Disease Control and Prevention ascribed 42 percent of all new TB cases to foreign-born people who have up to eight times higher incidence. Apparently, 66 percent of all TB cases coming to America originate in Mexico, the Philippines and Vietnam. [“Illegal Aliens and American Medicine,” by Madeleine Pelner Cosman, Ph.D., Esq.]

Chagas disease is yet another disease that has been imported from Latin America and has infiltrated America’s blood supply. “Chagas affects blood transfusions and transplanted organs,” cautioned Dr. Cosman. “No cure exists. Hundreds of blood recipients may be silently infected. After 10 to 20 years, up to 30 percent will die when their hearts or intestines, enlarged and weakened by Chagas, burst.”

Seven thousand cases of leprosy over the last 30 years may seem negligible, but “leprosy, a scourge in biblical days and in medieval Europe,” had been eradicated in the U.S. Now it’s back. By the reluctant admission of the New York Times, it was brought over from Asia and Latin America.

Other diseases with similar origins and vectors of transmissions are dengue fever, polio, malaria, Kawasaki disease, intestinal parasites and the ghastly, deadly brain worm. According to Wikipedia, the online Southern Poverty Law Center of encyclopedias, “cysticercosis in the U.S is an imported disease … found in immigrants from Mexico, Central and South America.”

A well-policed barrier is the definitive, non-aggressive method of defense against these ailments and afflictions. You don’t attack, arrest or otherwise molest undesirables; you keep them at bay, away.

Libertarian and leftist protest over any impediment to the free flow of people across borders is predicated not on the negative, leave-me-alone rights of the individual, but on the positive, manufactured right of human kind to venture wherever, whenever.

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