What have we learned in the 18 years since 9/11? Chris, Melanie, and Bryan discuss whether counterterrorism policy takes account of academic research on the subject. Going forward, the goal should be to implement the most cost-effective policies — and over time, to calm public anxiety about terrorism. Bryan gives a shout out to a bipartisan duo of Net Assessment fans, Chris gripes about NFL officiating, and Melanie offers her appreciation of the Constitution via an unlikely source: former Vice President Joe Biden.