Companies may want to think twice about how they instruct employees to keep mum during internal HR investigations, following a recent ruling by the National Labor Relations Board.

Last month, in a case involving Banner Estrella Medical Center, the NLRB ruled that a blanket policy requiring employee confidentiality in the course of an HR investigation violates employees’ rights to engage in concerted activity under Section 7 of the National Labor Relations Act. In other words, the board said: you can’t have a policy that keeps employees from talking to one another about problems in the workplace.