work to rule

A situation in which employees work only as much as has been agreed upon and no more, typically as a bargaining strategy (by unions). Instead of going on strike and stopping their work altogether, workers keep a more limited schedule than usual (i.e., no overtime), in order to slow down productivity. A: "The boss wants me to work some overtime tonight, but I can't, right?" B: "No. Because we're in a work to rule, you can only work your normal eight hours."