Officers are discouraged from even revealing that they work in the force
Social media, Facebook and Twitter in particular, has made it easy for anyone to share a lot more than they would have in the past and perhaps more than they should.For most people though, oversharing is going to lead to annoyed friends and maybe some embarrassment.
For some it's much more dangerous. It's taken a while, but the New York Police Department has finally issued some clear and rather strict policies over social media.
The document covers obvious stuff, such as not friending witnesses or sharing crime scene photos, to more subtle things such as not disclosing that they are police officers, within reason, or tagging colleagues.
Perhaps the biggest change is that officers are discouraged from revealing that they work for the police department. It makes sense though, while it's not a secret for many, some positions may require more discretion.