The antonyms for "jumping one case" are many, depending on the context of the sentence. If one is speaking of the act of physically jumping from one case to another, then the antonyms could be walking, standing still, or remaining seated. However, if the phrase is being used in a legal context, the antonyms could be sticking to one argument, remaining consistent, or avoiding inconsistencies. In a figurative sense, the act of jumping one case could be interpreted as indecisiveness or inconsistency, and the antonyms could be making a firm decision or sticking to one side. Ultimately, the antonyms depend on the meaning and context of the phrase.