lay down the law

Definition

› to repeatedly tell people what they should do, without caring about how they feel: People are fed up with him laying down the law the whole time. → See also brother-in-law → See also common-law → See also daughter-in-law → See also father-in-law → See also in-laws → See also martial law → See also mother-in-law → See also sister-in-law → See also son-in-law

(Definition of lay down the law from the Cambridge Learner's Dictionary © Cambridge University Press)