be on someone's case

be on someone's case

INFORMAL
If someone is on your case, they keep criticizing you or telling you that you should do something. Note: In the first two expressions, a case is a matter that is being dealt with by a lawyer or doctor, rather than referring to a box or suitcase. My parents are on my case night and day because they say I'm not studying enough. Note: You can also say that someone is getting on your case. I just didn't want Joanie getting on my case as well as everyone else. Note: If someone tells you to get off their case, they are telling you in an impolite way to stop criticizing them. Get off my case, will you?
See also: case, on

be on (or get off) someone's case

start (or stop) criticizing or hounding someone. informal
See also: case, on