Here’s a terrorism scenario: a stream of passengers walks through airport security one afternoon, each of whom is carrying a bottle over the TSA’s 3 ounce limit. Bored or sheepish, they each surrender their bottle to TSA screeners, who throw them into a nearby wastebin. However, each of the bottles contains a small quantity of high-explosive. One of them contains a timer and a detonator.
The result is a terrorist attack that was specifically enabled by policies designed to prevent terrorist attacks.
I think this scenario re-illustrates several things: