work to rule

Short definition from Wiktionary

Verb

1. 1
   To work slowly by strictly following all work rules, usually in a work-to-rule job action, as part of unionized labor protest.

Noun

1. 1
   Alternative spelling of work-to-rule.
2. 2
   A labor protest in which employees do only the minimum work required by the rules of a workplace, following safety or other regulations to the letter in order to cause a slowdown.

Adjective

1. 1
   Of or pertaining to such a protest.