The five years since 9/11, in retrospect, have been like a perpetual workshop in which Americans argue about the nature of their enemy and how to defeat him. Along the way, they have made plenty of mistakes, ranging from former secretary of state Colin Powell's claiming that 9/11 "should not be seen as something done by Arabs or Islamics," to not allowing an Arab to board an airplane because he wore a T-shirt bearing Arabic script. What impresses me, however, is how Americans have constantly, if slowly, improved their understanding of the enemy, as can be seen in everything from presidential rhetoric to airplane security. Much of this evolution has been improvised - using existing tools in new ways, preserving old laws but applying them in new circumstances. Here's one such example: Hamid Hayat, a 23-year-old cherry packer from Lodi, California, was convicted in April 2006 of providing material support to terrorists by attending a paramilitary training camp in Pakistan during 2003-04. In the course of a police interrogation, when asked who else had gone to the terror camps, Hayat fingered his 18-year-old American-born cousin, Jaber Ismail, saying he "went, like, two years ago." Did Jaber attend the same camp as him? "I'm not sure, but I'll say he went to a camp." Hayat later modified his story, saying that Ismail and another relative "didn't talk to me about going to camps or anything. But you know I'm sure they went to the camp ... cause they memorize the Holy Koran." JABER ISMAIL had, in fact, lived in Pakistan for four years, along with his father Muhammad, a 45-year-old naturalized US citizen born in Pakistan, his mother, and his two siblings. Predictably, Jaber explains his Pakistan years benignly: "I was memorizing the Koran because it was important to my mom." Jaber and Muhammad were so close to Hayat, they listed him as an emergency contact in their passports. On returning from Pakistan to Lodi on April 21, 2006, the Ismail family changed planes in Hong Kong. Three family members got permission to go on, but Jaber and his father were stopped, so they returned to Pakistan. On trying again two weeks later, they learned that, though not charged with a crime, they were on the US government's terrorism watch-list, and that they could only enter the United States after getting "clearance" from the embassy in Pakistan. That meant submitting to an FBI interrogation and to lie detector tests, which they refused to do. On Aug. 9, the American Civil Liberties Union filed a complaint with the US Department of Homeland Security (DHS) claiming the Ismails have been denied their civil rights. The ACLU lawyer, Julia Harumi Mass, states that "They want to come home and have an absolute right to come home. They can't be compelled to waive their constitutional rights under threat of banishment." Michael Barr, director of the aviation safety and security program at the University of Southern California deems it "very unprecedented" for US citizens to be rendered stateless in this fashion. Usama Ismail, 20, complains that his brother and father are being treated "like foreigners or something." Is the Ismails' exclusion legal? TO GET a reading on the feds' legal basis, I turned to William West, former chief of the National Security Section for the Bureau of Immigration and Customs Enforcement in Miami, Florida. "It is a rare decision, but within the legal pale," he explained to me. "Section 215 of the Immigration and Nationality Act, 8 USC 1185 allows for the 'travel control' of the entry and departure of citizens. US citizens use their passports only within the rules, regulations, and proscriptions as issued and decided by the president. Travel restrictions on US citizens are seldom utilized (and usually to keep criminal or national-security suspects from fleeing). The law, however, does also allow for entry control." West expects that the Ismails "ultimately will be allowed back into the country. But in the short term, DHS has a legal basis for excluding them." The DHS not only applied the law to scrutinize possibly dangerous Islamists but its actions suggest a possible conceptual breakthrough, signaling that the US government sees the "nationality" of radical Islam to be incompatible with American citizenship. Thus do Americans improvise and make gradual progress in their war on terror.