work-to-rule
noun [ C, usually singular ]
UK uk/ˌwɜːktəˈruːl/ us(US work-to-contract) WORKPLACE
a situation in which employees only do as much work as their contracts say they must do, as a way of showing that they are unhappy about pay, conditions, etc., but do not strike (= stop working completely):
On Thursday the airline had to charter 10 aircraft to counter industrial action by its pilots, who are on a work-to-rule.