After the 9/11 attacks, when 19 Muslim terrorists — 15 from Saudi Arabia, two from the United Arab Emirates and one each from Egypt and Lebanon, 14 with "al" in their names — took over commercial aircraft with box-cutters, the government banned sharp objects from planes.
Airport security began confiscating little old ladies' knitting needles and breaking the mouse-sized nail files off of passengers' nail clippers. Surprisingly, no decrease in the number of hijacking attempts by little old ladies and manicurists was noted.
After another Muslim terrorist, Richard Reid, AKA Tariq Raja, AKA Abdel Rahim, AKA Abdul Raheem, AKA Abu Ibrahim, AKA Sammy Cohen (which was only his eHarmony alias), tried to blow up a commercial aircraft with explosive-laden sneakers, the government prohibited more than 3 ounces of liquid from being carried on airplanes.
All passengers were required to take off their shoes for special security screening, which did not thwart a single terrorist attack, but made airport security checkpoints a lot smellier.
After Muslim terrorist Umar Farouk Abdulmutallab of Nigeria tried to detonate explosive material in his underwear over Detroit last Christmas, the government began requiring nude body scans at airports.
The machines, which cannot detect chemicals or plastic, would not have caught the diaper bomber. So, again, no hijackers were stopped, but being able to see passengers in the nude boosted the morale of airport security personnel by 22 percent.
After explosives were inserted in two ink cartridges and placed on a plane headed to the United States from the Muslim nation of Yemen, the government banned printer cartridges from all domestic flights, resulting in no improvement in airport security, while requiring ink cartridges who traveled to take Amtrak.