The phrase "are on one's case" can be defined as the act of someone constantly nagging, criticizing, or bothering another person. Some antonyms for this phrase could include "leaving someone alone," "giving someone space," or "not micromanaging." Other synonyms that could be used in place of "are on one's case" include "picking on someone," "hassling," or "hounding." It's important to be mindful of our language and how we approach others, as constantly being "on someone's case" can be detrimental to their mental health and wellbeing. Instead, practicing kindness and empathy towards others can go a long way in building positive relationships.