security is about planning for the worst (Score 5, Informative)

If you work in a facility that requires you to not bring media into work so that you can't remove secret information, you deserve to be fired for bringing in a flash drive. Trusted insiders are the greatest threat, hence the need for policies. Such policies are very enforceable, and hold up under the law for the dismissal of employees who violate them. A good policy sets up not only what's forbidden, but also what to do if a security breach happens. Check http://www.sans.org/. If an employee is determined enough, he or she might just find a less restrictive job.