This ruling by the US 4th Circuit throws cold water on the idea you have no 1st amendment rights. Public employees have more 1st amendment rights than private employees. It is a gray area and a legal minefield for employers taking adverse actions for posts made outside of work. https://www.techdirt.com/articles/20161215/18455936294/court-says-police-chiefs-social-media-policy-violated-first-amendment.shtml