Facebook had more than 1 billion daily active users around the world as of September. That’s a lot of timeline posts and status updates, and many involve the workplace. This leaves employers in a difficult spot as they try to figure out what types of employee online speech get legal protections.

The answer isn’t always simple. At times the National Labor Relations Board, which has taken on the role of arbiter of social media and employment issues, has ruled that posts by employees on Facebook and other social media that seem like fireable offenses are really, in fact, “protected concerted activity,” covered by Section 7 of the National Labor Relations Act.