It took the case of "JihadJane" to illuminate what should have been obvious by now: Anyone who claims to be able to identify a potential terrorist by appearance or nationality is delusional. There's a reason why all of us have to take our shoes off at the airport.

For years, some voices on the right have argued for racial-ethnic-religious profiling. After the Christmas Day attempt to bomb an airliner, Newt Gingrich wrote that the time has come "to profile for terrorists and to actively discriminate based on suspicious terrorist information." Gingrich said that "because our elites fear politically incorrect honesty, they believe that it is better to harass the innocent, delay the harmless, and risk the lives of every American than to do the obvious, the effective, and the necessary."

I won't quote any more of Gingrich's lengthy screed, but any reader would conclude that if the former House speaker were manning an airport metal detector, he'd give extra scrutiny to anyone who resembled Umar Farouk Abdulmutallab — the Nigerian accused in the Christmas Day attempt — while essentially giving a pass to someone like Colleen LaRose, 46, of Pennsburg, Pa.

Which, as it turns out, would have been a dangerous mistake.

According to a federal indictment, LaRose was a regular on radical Islamist Web sites who sometimes called herself JihadJane. She allegedly had expressed a desire to become a martyr for Islam, and prosecutors charge that before her arrest last October she was actively plotting to kill a Swedish artist who had drawn a cartoon depicting the Prophet Muhammad as a dog.

Now, it has to be pointed out that if the story told in the indictment is true, LaRose does not seem to have been the brightest bulb in the jihadist firmament. In her Internet postings she appears to have made little or no attempt to hide her identity, aside from choosing a nom de guerre that is the equivalent of a flashing red light. But Abdulmutallab was hardly a diabolical mastermind, either. What the two have in common is that they both seem to have been lonely and alienated, to have been searching for meaning in their lives, and to have made terrible choices.

What they don't have in common is anything else. Abdulmutallab is a young, black, wealthy, foreign man with a Muslim-sounding name. LaRose is a blond-haired, blue-eyed, middle-aged white woman who grew up in Texas, dropped out of high school, married and divorced a couple of times, met a boyfriend from Pennsylvania and ended up living in a small town 50 miles from Philadelphia.

On the Internet, she allegedly boasted that her appearance and nationality would allow her to travel freely and without scrutiny as she went about her mission — apparently self-assigned — of killing Swedish artist Lars Vilks. There is no indication that she had any actual contact with al-Qaida, which has put a $100,000 bounty on Vilks' head. According to the indictment, LaRose traveled to Europe to meet with unnamed, like-minded individuals, and also allegedly stole her American boyfriend's passport with the idea of giving it to a fellow jihadist to use. But it does not appear she had the slightest idea of how to kill anybody.

Still, aspiring terrorists can stumble into becoming real ones. And what profile would have picked her out of the crowd?

LaRose may be unique because of her looks, but she is hardly the only American thought by officials to have been seduced by the ideology of jihad. Omar Hammami, who as a teenager was president of his sophomore class in Daphne, Ala., is a key figure in al-Shabab, an Islamist insurgent group in Somalia that is affiliated with al-Qaida. In December, five men from Northern Virginia were arrested in Pakistan and accused of trying to join al-Qaida.

"Washington is still avoiding being intellectually honest about the war we are in," Gingrich claims. But intellectual honesty requires taking into account the fact that terrorists and would-be terrorists don't come from central casting. This means that at airports and elsewhere, there has to be equal-opportunity scrutiny.

To "actively discriminate," as Gingrich and others recommend, would do more than single out a lot of innocent people. It would guarantee that we miss the next JihadJane — who might be taking instruction from leaders more nefarious than her cats.