We’ve been telling readers for years that you need to be very careful about what you say and post on social media, whether Facebook, Twitter, Snapchat, Instagram, or other sites. It can be used against you in divorce proceedings, in lawsuits and criminal trials, and, of course, in the court of popular opinion. Now add another place it can be used against you to the list: during the background check for your Federal security clearance. (Full text of directive below.)