This week there has been much talk in the U.S. news about how Andrew Speaker, the now notorious TB patient (more specifically extensively drug-resistant tuberculosis, or XDR-TB), apparently very easily circumvented security controls to come back into the U.S. via Canada.
My heading is a paraphrase of a longer quote I really like from Charles Schumer that he made about this incident, but that also applies very nicely to all information security practices.