Can my employer discipline me for protesting against one of its policies or practices that affects me and other employees?
Maybe not. The National Labor Relations Act prohibits employers from disciplining or discharging employees who engage in a “concerted activity” aimed at making conditions better for a group of employees. This might include speaking out at an employee meeting or distributing a complaint or notice to other employees. You do not have to be in a union to be protected by the NLRA, but your activity must be aimed at helping a group of employees and inducing group action.